Cytopheresis cartridges and use thereof

ABSTRACT

The present invention relates to a cytopheretic cartridge for use in treating and/or preventing inflammatory conditions within a subject and to related methods. More particularly, the invention relates to a cytopheretic cartridge that includes a housing and, disposed within the housing, a solid support capable of sequestering activated leukocytes and/or platelets.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.13/878,954, filed Jul. 17, 2013, which is a U.S. National StageApplication filed under 35 U.S.C. § 371 of International PatentApplication No. PCT/US2011/056469, filed Oct. 14, 2011, which claims thebenefit of and priority to U.S. Provisional Application No. 61/393,805,filed Oct. 15, 2010, the complete disclosures of each of which areincorporated herein by reference.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

This invention was made with government support under DK080529 awardedby the National Institutes of Health, under W81XWH-05-2-0010 awarded bythe U.S. Army Medical Research and Materiel Command, and TR000630awarded by the National Institutes of Health. The government has certainrights in this invention.

FIELD OF THE INVENTION

The present invention relates to cartridges, systems, and methods fortreating and/or preventing inflammatory conditions within a subject.More particularly, the present invention relates to cartridges andsystems for sequestering and reducing the inflammatory activity of cellsassociated with inflammation, such as leukocytes and platelets, and torelated methods for sequestering and reducing the inflammatory activityof such cells.

BACKGROUND

Various medical conditions are caused, exacerbated, and/or characterizedby unwanted inflammation. Infections, such as bacterial, viral, andfungal infections; trauma, such as from falls, automobile accidents, gunand knife wounds; cardiovascular events, such as aneurysms and ischemicevents often associated with surgery; and endogenous inflammatoryreactions, such as pancreatitis and nephritis, often lead to profounddysfunction of the homeostatic mechanisms involved in regulatingcardiovascular and immune system function. Several of these conditions,such as ischemia and infections, through abnormal or excessiveactivation of the immune system, may result in cardiovasculardysfunction that can develop over a period of hours to days, and which,under certain circumstances, can be life threatening or even fatal.

Certain cell types are critical to the dysfunction of the cardiovascularand immune systems. For example, leukocytes, especially neutrophils,contribute to the pathogenesis and progression of various inflammatoryconditions, including systemic inflammatory response syndrome (SIRS),sepsis, ischemia/reperfusion injury and acute respiratory distresssyndrome (ARDS) (see, e.g., Kaneider et al. (2006) FEBS J 273:4416-4424;Maroszynska et al. (2000) ANN. TRANSPLANT. 5(4):5-11). In addition,activated platelets enhance leukocyte adhesion and promote leukocyteactivation. While inflammation and a systemic immune response can bebeneficial in certain circumstances, they can also be fatal.

Inflammatory injury in organs can result in microvascular damage inducedby leukocyte activation and aggregation, as well as platelet activationand aggregation. These activated cells can contribute to microvascularstasis and reperfusion injury by releasing toxic compounds into apatient's tissue. In acute inflammation, activated leukocytes andplatelets interact as a gel-like structure within the vessel. This leadsto poor perfusion of the tissue, which normally is supplied with oxygenand nutrients by the capillaries. Activated leukocytes additionallycause damage by extravasating across the endothelium into the tissue,where they release toxic agents normally intended to destroy invadingmicrobes or clear out necrotic debris. Activated platelets additionallycause damage by enhancing the activation and endothelial transmigrationof leukocytes. When these processes are not controlled, they can lead totissue injury and death.

SIRS is the thirteenth leading cause of death in the United States ofAmerica. Severe sepsis with SIRS occurs in 200,000 patients annually inthe U.S. with a mortality rate of 30-40%, even with use of intensivecare units and broad spectrum antibiotics. SIRS is diagnosed largely onobserved physiological changes such as increase (fever) or decrease(hypothermia) in body temperature, increased heart rate (tachycardia),increased respiration rate (tachypnea), elevated or diminished whiteblood cell counts, and inadequate perfusion of tissues and organs. Adecrease in blood pressure is a complication associated with SIRS thatoccurs late in the course of the syndrome. Specifically, a decrease inblood pressure can reflect the development of shock and contribute tomultiple organ failure, which is a leading cause of death in thesepatients. Septic shock is a condition that includes the clinicalobservations of the presence of an infection and a drop in bloodpressure despite fluid resuscitation and proper cardiac blood output. Asimilar condition, sepsis syndrome, includes similar physiologicalsignals with no evidence of any type of infection. Other insults, whichinduce a sepsis-like condition include pancreatitis, burns, ischemia,multiple trauma and tissue injury (often due to surgeries andtransplants), haemorrhagic shock and immune-mediated organ dysfunction.

The standard therapies for SIRS and septic shock involve administrationof antibiotics to bring the infection under control and fluid/colloidtherapy to maintain circulating blood volume. Frequently, drugs thathelp maintain blood pressure, such as dopamine and vasopressin, are alsoadministered.

Cardiopulmonary bypass (CPB) can induce SIRS, activating complement andcoagulation systems and stimulating cytokine production. A large numberof therapeutic approaches are under investigation to limit theactivation and accumulation of leukocytes during CPB. In fact, animaland early clinical data suggest amelioration of lung and kidney damageduring CPB surgery with the use of leukocyte depletion filters (see,e.g., Gu et al. (1996) J. THORAC. CARDIOVASC. SURG. 112:494-500; Bollinget al. (1997) J. THORAC. CARDIOVASC. SURG. 113:1081-1090; Tang et al.(2002) Ann. Thorac. Surg. 74:372-377; Alaoj a et al. (2006) J. THORAC.CARDIOVASC. SURG. 132:1339-1347). It appears, however, that dialysis canproduce transient neutropenia (see, Kaplow et al. (1968) JAMA 203:1135).

There remains a need for improved treatments of inflammatory conditions,such as cardiovascular shock, sepsis, systemic inflammatory responsesyndrome and anaphylaxis.

SUMMARY OF THE INVENTION

Inflammatory conditions often arise from the activation of cellsassociated with inflammation, such as leukocytes and platelets. Thepresent invention relates to cartridges, systems and related methods fortreating and/or preventing inflammatory conditions by extracorporeallysequestering leukocytes and/or platelets and inhibiting or deactivatingtheir inflammatory action. For example, these cells can be deactivatedand/or their release of pro-inflammatory substances can be inhibited.

As leukocytes and platelets are normally found in the bloodstream, theycan be sequestered by passing blood, or another body fluid containingthe cells, through the interior of a device providing a surface thatsequesters these cells for a period of time. It has now been discoveredthat the number of leukocytes and/or platelets sequestered needs to becontrolled to treat the inflammatory condition without removing too manycells so as to cause a deficiency of those cells. For example, the lossof too many leukocytes can result in the life threatening and even fatalcondition known as leucopenia. Similarly, the loss of too manyneutrophils can result in the life threatening condition known asneutropenia. The loss of too many platelets can result inthrombocytopenia. Furthermore, the volume of fluid available from asubject (for example, infants, children and severely ill,hemodynamically unstable patients) can have a significant effect on theefficacy of the treatment. Accordingly, the choice of a SCD cartridgehaving the appropriate ratio of active surface area on the solid supportfor sequestering cells to the inner volume of the SCD cartridge housingcan have a profound effect on the efficacy of the treatment in a givenpatient.

In one aspect, the invention provides a cartridge for treating activatedleukocytes, activated platelets, or both activated leukocytes andactivated platelets. The cartridge includes a rigid housing with a fluidinlet port, a fluid outlet port, and an inner volume (IV) through whichthe body fluid can pass. The inner volume is in fluid flow communicationwith the fluid inlet port and the fluid outlet port. A solid support ispositioned within the housing, so that at least a portion of the solidsupport is located between the fluid inlet port and the fluid outletport. The solid support defines a fluid contacting surface with asurface area (SA) capable of sequestering an activated leukocyte and/oran activated platelet if present in a body fluid entering the housingvia the fluid inlet port. In certain embodiments, the SA/IV ratio of theSCD cartridge is greater than 150 cm⁻¹ (for example, in the range of 150cm⁻¹ to 1,500 cm⁻¹, in the range of 300 cm⁻¹ to 1,000 cm⁻¹, in the rangeof 300 cm⁻¹ to 800 cm⁻¹, in the range of 300 cm⁻¹ to 600 cm⁻¹, in therange of 400 cm⁻¹ to 800 cm⁻¹, in the range of 400 cm⁻¹ to 600 cm⁻¹, orin the range of 200 cm⁻¹ to 600 cm⁻¹).

In certain embodiments, the IV optionally is less than 300 cm³, and maybe less than 150 cm³ or less than 100 cm³. In some embodiments, the IVmay be in the range of from 10 cm³ to 150 cm³, for example, from 75 cm³to 150 cm³, from 15 cm³ to 120 cm³, or from 20 cm³ to 80 cm³. In certainembodiments, the SA may exceed 0.8 m². In other embodiments, the SA maybe in the range of 0.1 m² to 10.0 m² or 0.1 m² to 5.0 m². For example,the SA may be in the range of from 0.1 m² to 0.4 m², from 0.4 m² to 0.8m², from 0.8 m² to 1.2 m², from 1.2 m² to 1.6 m², from 1.6 m² to 2.0 m²,from 2.0 m² to 2.4 m², from 2.4 m² to 2.8 m², from 2.8 m² to 3.2 m²,from 3.2 m² to 3.6 m², from 3.6 m² to 4.0 m², from 4.0 m² to 4.4 m²,from 4.4 m² to 4.8 m², from 4.8 m² to 5.2 m², from 5.2 m² to 5.6 m²,from 5.6 m² to 6.0 m², from 6.0 m² to 6.4 m², from 6.4 m² to 6.8 m², orfrom 6.8 m² to 7.2 m².

The solid support can be defined by one or more fibers (for example,hollow or solid fibers), one or more planar support members, or acombination thereof. The solid support can be a membrane that is porous,semi-porous, or non-porous. Furthermore, the solid support may befabricated from a biocompatible material, for example, polysulfone orpolyethersulfone, and/or may have one or more cell-adhesion moleculesattached thereto.

If the solid support occupies a greater percentage of the volume of thecartridge, this reduces the inner volume of the cartridge, increasingthe SA/IV ratio. Accordingly, in this aspect of the invention, the solidsupport is disposed in the housing at a packing density of 20%-65%,facilitating a favorable SA/IV ratio.

In another aspect, the invention provides cartridges with enhancedsurface areas of greater than 2.6 m² for sequestering activatedleukocytes, activated platelets, or both activated leukocytes andactivated platelets, and methods of using the cartridges to treatsubjects. The cartridge comprises a rigid housing with a fluid inletport, a fluid outlet port, and an inner volume (IV) through which thebody fluid can pass. The inner volume is in fluid flow communicationwith the fluid inlet port and the fluid outlet port. A solid support ispositioned within the housing, so that at least a portion of the solidsupport is located between the fluid inlet port and the fluid outletport. The solid support defines a fluid contacting surface with asurface area (SA) capable of sequestering an activated leukocyte and/oran activated platelet if present in a body fluid entering the housingvia the fluid inlet port. In this embodiment, the SA is more than 2.6 m²and may be from 3.0 m² to 10.0 m², from 3.0 m² to 5.0 m², from 3.0 m² to3.5 m², from 3.5 m² to 4.0 m², from 4.0 m² to 4.5 m², from 4.5 m² to 5.0m², from 5.0 m² to 5.5 m², from 5.5 m² to 6.0 m², from 6.0 m² to 6.5 m²,from 6.5 m² to 7.0 m², from 7.0 m² to 7.5 m², from 7.5 m² to 8.0 m²,from 8.0 m² to 8.5 m², from 8.5 m² to 9.0 m², from 9.0 m² to 9.5 m², orfrom 9.5 m² to 10.0 m², for example.

In certain embodiments, the IV optionally is less than 300 cm³, and maybe less than 150 cm³ or less than 100 cm³. In some embodiments, the IVmay be in the range of from 10 cm³ to 150 cm³, for example, from 75 cm³to 150 cm³, from 15 cm³ to 120 cm³, or from 20 cm³ to 80 cm³. The SA/IVratio of the SCD cartridge may be greater than 150 cm⁻¹ (for example, inthe range of 150 cm⁻¹ to 1,500 cm⁻¹, in the range of 300 cm⁻¹ to 1,000cm⁻¹, in the range of 300 cm⁻¹ to 800 cm⁻¹, in the range of 300 cm⁻¹ to600 cm⁻¹, in the range of 400 cm⁻¹ to 800 cm⁻¹, in the range of 400 cm⁻¹to 600 cm⁻¹, or in the range of 200 cm⁻¹ to 600 cm⁻¹).

The solid support can be defined by one or more fibers (for example,hollow or solid fibers), planar support members, or a combinationthereof. The solid support can be a membrane that is porous,semi-porous, or non-porous. Furthermore, the solid support may befabricated from polysulfone and/or may have one or more cell-adhesionmolecules attached thereto.

In a further aspect, the invention provides cartridges having aplurality of solid fibers. The cartridge comprises a rigid housing witha fluid inlet port, a fluid outlet port, and an inner volume (IV)through which a body fluid can pass. The inner volume is in fluid flowcommunication with the fluid inlet port and the fluid outlet port.Disposed within the housing is a solid support that includes a pluralityof solid fibers, optionally including polysulfone and/orpolyethersulfone. The solid support defines a fluid contacting surfacewith a surface area (SA) capable of sequestering an activated leukocyteand/or an activated platelet if present in a body fluid entering thehousing via the fluid inlet port. In this embodiment, the SA/IV ratio ofthe cartridge is greater than 25 cm⁻¹, and may be greater than 80 cm⁻¹,or greater than 150 cm⁻¹ (for example, in the range of 150 cm⁻¹ to 1,500cm⁻¹, in the range of 150 cm⁻¹ to 1,000 cm⁻¹, in the range of 25 cm⁻¹ to800 cm⁻¹, or in the range of 80 cm⁻¹ to 800 cm⁻¹). The SA may be greaterthan 0.09 m², or may be in the range of from 0.09 m² to 10.0 m². Forexample, the SA may be in the range of from 0.1 m² to 0.4 m², from 0.4m² to 0.8 m², from 0.8 m² to 1.2 m², from 1.2 m² to 1.6 m², from 1.6 m²to 2.0 m², from 2.0 m² to 2.4 m², from 2.4 m² to 2.8 m², from 2.8 m² to3.2 m², from 3.2 m² to 3.6 m², from 3.6 m² to 4.0 m², from 4.0 m² to 4.4m², from 4.4 m² to 4.8 m², from 4.8 m² to 5.2 m², from 5.2 m² to 5.6 m²,from 5.6 m² to 6.0 m², from 6.0 m² to 6.4 m², from 6.4 m² to 6.8 m²,from 6.8 m² to 7.2 m², from 7.2 m² to 7.6 m², from 7.6 m² to 8.0 m²,from 8.0 m² to 8.4 m², from 8.4 m² to 8.8 m², from 8.8 m² to 9.2 m²,from 9.2 m² to 9.6 m², from 9.6 m² to 10.0 m². The IV optionally is lessthan 150 cm³. In some embodiments, the IV may be in the range of from 75cm³ to 150 cm³ or from 5 cm³ to 50 cm³.

The invention provides a method for processing an activated leukocyte,an activated platelet, or both an activated leukocyte and an activatedplatelet contained within a body fluid. The method uses a cartridge thatincludes a rigid housing with a fluid inlet port, a fluid outlet port,and an inner volume (IV) through which the body fluid can pass. Theinner volume is in fluid flow communication with the fluid inlet portand the fluid outlet port. A solid support is positioned within thehousing so that at least a portion of which is located between the fluidinlet port and the fluid outlet port and defines a fluid contactingsurface. The fluid contacting surface has a surface area (SA) capable ofsequestering an activated leukocyte and/or an activated platelet ifpresent in a body fluid entering the housing via the fluid inlet port.The SA/IV ratio is greater than 80 cm⁻¹, and optionally greater than 100cm⁻¹, greater than 125 cm⁻¹, or greater than 150 cm⁻¹ (for example, inthe range of 80 cm⁻¹ to 1,500 cm⁻¹, 150 cm⁻¹ to 1,500 cm⁻¹, in the rangeof 300 cm⁻¹ to 1,000 cm⁻¹, in the range of 300 cm⁻¹ to 800 cm⁻¹, in therange of 300 cm⁻¹ to 600 cm⁻¹, in the range of 400 cm⁻¹ to 800 cm⁻¹, orin the range of 400 cm⁻¹ to 600 cm⁻¹).

In certain embodiments, the IV is optionally restricted to less than 150cm³, such as in the range of from 10 cm³ to 150 cm³, from 75 cm³ to 150cm³, from 15 cm³ to 120 cm³, or from 20 cm³ to 80 cm³. The SA may be inthe range of 0.1 m² to 10.0 m² or 0.1 m² to 5.0 m². In certainembodiments, the SA may be in the range of from 0.1 m² to 0.4 m², from0.4 m² to 0.8 m², from 0.8 m² to 1.2 m², from 1.2 m² to 1.6 m², from 1.6m² to 2.0 m², from 2.0 m² to 2.4 m², from 2.4 m² to 2.8 m², from 2.8 m²to 3.2 m², from 3.2 m² to 3.6 m², from 3.6 m² to 4.0 m², from 4.0 m² to4.4 m², from 4.4 m² to 4.8 m², from 4.8 m² to 5.2 m², from 5.2 m² to 5.6m², from 5.6 m² to 6.0 m², from 6.0 m² to 6.4 m², from 6.4 m² to 6.8 m²,or from 6.8 m² to 7.2 m².

In the method, a body fluid from a subject is introduced into thehousing via the fluid inlet port under conditions that permitsequestration of an activated leukocyte and/or an activated platelet onthe fluid contacting surface of the solid support. The body fluid isoptionally permitted to exit the cartridge via the fluid outlet port ata flow rate in the range of 10 cm³/minute to 8,000 cm³/minute, such as,for example, 50 cm³/minute to 8,000 cm³/minute.

In certain embodiments, the solid support can be defined by one or morefibers (for example, hollow or solid fibers), one or more planar supportmembers, or a combination thereof. The solid support can be a membranethat is porous, semi-porous, or non-porous. Furthermore, the solidsupport may be fabricated from a biocompatible material such aspolysulfone or polyethersulfone, and may have one or more cell-adhesionmolecules attached thereto.

In certain embodiments, the method can also include treating thesequestered leukocyte and/or platelet to inhibit the release of apro-inflammatory substance or to deactivate the leukocyte and/orplatelet. The leukocyte and/or platelet can be sequestered for a time(e.g., at least one second, at least one minute, at least five minutes,at least fifteen minutes, or at least an hour) sufficient to inhibit therelease of the pro-inflammatory substance or to deactivate the leukocyteand/or the platelet. A calcium chelator such as citrate can be used toinhibit the release of the pro-inflammatory substance or to deactivatethe leukocyte or platelet. After treatment, the leukocyte or plateletcan optionally be returned back to the subject.

In another aspect, the invention provides methods for treating a subjecthaving or at risk of developing an inflammatory condition. Theinflammatory condition is optionally selected from the group consistingof systemic inflammatory response syndrome (SIRS), polyarteritis,Wegener's granulomatosis, autoimmune vasculitis, anti-neutrophilcytoplasmic antibody (ANCA) vasculitis, extracorporeal membraneoxygenation (ECMO), cardiopulmonary bypass syndrome, acute respiratorydistress syndrome (ARDS), acute lung injury (ALI), chronic obstructivepulmonary disease (COPD), sepsis, rheumatoid arthritis, systemic lupuserythematosus, inflammatory bowel disease, multiple sclerosis (MS),psoriasis, allograft rejection, asthma, acute renal failure, chronicrenal failure (CRF), end stage renal disease (ESRD), cardiorenalsyndrome (CRS), chronic heart failure (CHF), stroke, myocardialinfarction (MI), hepatorenal syndrome, cirrhosis of the liver, diabetesmellitus (type 2 diabetes), and acute organ failure from ischemicreperfusion injury to myocardium, central nervous system, liver, kidney,or pancreas.

The treatment method uses a cartridge that includes a rigid housing witha fluid inlet port, a fluid outlet port, and an inner volume (IV)through which the body fluid can pass. A solid support is positionedwithin the housing so that at least a portion of which is locatedbetween the fluid inlet port and the fluid outlet port and defines afluid contacting surface. The fluid contacting surface has a surfacearea (SA) capable of sequestering an activated leukocyte if present in abody fluid entering the housing via the fluid inlet port. The SA/IVratio is greater than 80 cm⁻¹, greater than 100 cm⁻¹, greater than 125cm⁻¹, greater than 150 cm⁻¹ (for example, in the range of 80 cm⁻¹ to1,500 cm⁻¹, 150 cm⁻¹ to 1,500 cm⁻¹, in the range of 300 cm⁻¹ to 1,000cm⁻¹, in the range of 300 cm⁻¹ to 800 cm⁻¹, in the range of 300 cm⁻¹ to600 cm⁻¹, in the range of 400 cm⁻¹ to 800 cm⁻¹, or in the range of 400cm⁻¹ to 600 cm⁻¹).

In certain embodiments, the IV is optionally restricted to less than 150cm³, such as in the range of from 10 cm³ to 150 cm³, from 75 cm³ to 150cm³, from 15 cm³ to 120 cm³, or from 20 cm³ to 80 cm³. The SA may be inthe range of 0.1 m² to 10.0 m² or 0.1 m² to 5.0 m². In certainembodiments, the SA may be in the range of from 0.1 m² to 0.4 m², from0.4 m² to 0.8 m², from 0.8 m² to 1.2 m², from 1.2 m² to 1.6 m², from 1.6m² to 2.0 m², from 2.0 m² to 2.4 m², from 2.4 m² to 2.8 m², from 2.8 m²to 3.2 m², from 3.2 m² to 3.6 m², from 3.6 m² to 4.0 m², from 4.0 m² to4.4 m², from 4.4 m² to 4.8 m², from 4.8 m² to 5.2 m², from 5.2 m² to 5.6m², from 5.6 m² to 6.0 m², from 6.0 m² to 6.4 m², from 6.4 m² to 6.8 m²,or from 6.8 m² to 7.2 m².

In the method, a body fluid from a subject is introduced into thehousing via the fluid inlet port under conditions that permitsequestration of an activated leukocyte on the fluid contacting surfaceof the solid support. The body fluid is optionally permitted to exit thecartridge via the fluid outlet port at a flow rate in the range of 10cm³/minute to 8,000 cm³/minute, such as, for example, 50 cm³/minute to8,000 cm³/minute.

In certain embodiments, the solid support can be defined by one or morefibers (for example, hollow or solid fibers), one or more planar supportmembers, or a combination thereof. The solid support can be a membranethat is porous, semi-porous, or non-porous. Furthermore, the solidsupport may be fabricated from polysulfone and may have one or morecell-adhesion molecules attached thereto.

In certain embodiments, the method optionally further includes treatinga sequestered leukocyte and/or platelet to reduce the risk of developinginflammation associated with the inflammatory condition or to alleviateinflammation associated with the inflammatory condition. The leukocytemay be sequestered for a time (e.g. less than one minute, at least oneminute, at least five minutes, at least fifteen minutes, or at least anhour) sufficient to deactivate the leukocyte and/or inhibit the releaseof a pro-inflammatory substance. For example, a calcium chelator such ascitrate, ethylenediaminetetraacetic acid (EDTA), or phosphonates, may beused to deactivate the leukocyte and/or the platelet and/or inhibit therelease of a pro-inflammatory substance. Once treated, the leukocyteand/or the platelet can optionally be returned back to the subject.

In each of the foregoing aspects of the invention, the SCD cartridgepreferably is sterile and is made of one or more biocompatiblematerials, particularly in the fluid-contacting portions of the housingand the solid support. In certain embodiments, in order to extendcontact with the fluid while minimizing turbulence, the solid supportpreferably is oriented substantially parallel to the direction of fluidflow within the cartridge. In other embodiments, the fluid inlet portand the fluid outlet port are optionally dimensioned to permit a flowrate through the housing in the range of 10 cm³/minute to 8,000cm³/minute or 50 cm³/minute to 8,000 cm³/minute. To achieve these flowrates, the fluid inlet and fluid outlet ports optionally andindependently have a minimum cross section of no less than 0.01 cm², noless than 0.1 cm², no less than 0.2 cm², no less than 0.4 cm², no lessthan 0.6 cm², no less than 0.8 cm², or no less than 1.0 cm², or eachhave a cross section in the range of from 0.01 cm² to 1.0 cm².Furthermore, in certain embodiments, the housing is configured to createa shear force of less than 100 dynes/cm² when a body fluid enters thehousing through the fluid inlet port and exits the housing through thefluid outlet port at, for example a rate of 250, 500, 1000, 2000, or4000 cm³/minute. In various embodiments of the invention, the fluidinlet and fluid outlet port are both be disposed on one side of thehousing, or on opposite sides of the housing. In some embodiments, thehousing has a first end and a second end opposite the first end, and thefluid inlet port is configured to permit fluid flow through the firstend while the fluid outlet port is configured to permit fluid flowthrough the second end. In certain embodiments, the solid support isdisposed in the housing at a packing density of 15%-70%, 20%-65%,20%-60%, 30%-60%, 40%-55%, or 40%-50%.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing aspects and embodiments of the invention may be more fullyunderstood by reference to the following detailed description andclaims.

FIG. 1A is a schematic, cross-sectional representation of an exemplarySCD cartridge containing a plurality of hollow fibers. FIG. 1B-1D areschematic, cross-sectional representations of a SCD cartridge containinga plurality of solid fibers and/or planar support members.

FIG. 2A is a schematic representation of a fluid circuit containing aSCD cartridge where the intracapillary space (ICS) has both ends capped.FIG. 2B is a schematic representation of an embodiment similar to FIG.2A except that ultrafiltrate (UF) is collected from a SCD cartridgehaving only one end of the ICS capped. FIG. 2C is a schematicrepresentation of an embodiment of a fluid circuit containing a firstdevice, for example, a hemofiltration device, and a SCD cartridge thatincludes an ICS with both ends capped. FIG. 2D is a schematicrepresentation of an embodiment similar to FIG. 2C except thatultrafiltrate (UF) is collected from the SCD cartridge where only oneend of the ICS is capped.

FIGS. 3A and 3B are schematic representations of embodiments of systemconfigurations that can be used as a CPB circuit. In FIG. 3A the circuitcomprises a recirculation loop and in FIG. 3B, the fluid circuit lacks arecirculation loop.

FIG. 4 is a schematic representation of an embodiment of a systemconfiguration used in treating a subject with sepsis.

FIGS. 5A-F are graphical depictions of changes in cardiovascularparameters of subjects with sepsis treated an F-40 SCD device in thepresence of heparin (SCD-H); an F-40 SCD device in the presence ofcitrate (SCD-C, F-40); or an F-80A SCD device in the presence of citrate(SCD-C, F-80A). Results are shown for mean arterial blood pressure (FIG.5A); cardiac output (FIG. 5B); systemic vascular resistance (FIG. 5C);pulmonary vascular resistance (FIG. 5D); renal vascular resistance (FIG.5E); and hematocrit (FIG. 5F).

FIGS. 6A-D are graphical depictions of changes in renal parameters ofsubjects with sepsis treated an F-40 SCD device in the presence ofheparin (SCD-H); an F-40 SCD device in the presence of citrate (SCD-C;F-40); or an F-80A SCD device in the presence of citrate (SCD-C; F-80A).Results are shown for blood urea nitrogen (BUN) (FIG. 6A); creatinine(FIG. 6B); renal blood flow (FIG. 6C); and cumulated urine output (FIG.6D).

FIG. 7 is a graphical depiction of survival times for subjects withsepsis treated with an F-40 SCD device in the presence of heparin(SCD-H) or with an F-40 or F-80A SCD device in the presence of citrate(SCD-C).

FIG. 8 is a bar graph depicting survival times for subjects with sepsistreated an F-40 SCD device in the presence of heparin (SCD-H); an F-40SCD device in the presence of citrate (F-40, SCD-C); or an F-80A SCDdevice in the presence of citrate (F-80A, SCD-C). The impact of SCD-Cvs. SCD-H on survival time in the septic pig is shown with p<0.005(F-40)and p<0.0004 (F-80A).

FIGS. 9A-D are a series of light microscopy photographs showingleukocyte attachment and aggregation along the outer surface of SCDmembranes.

FIGS. 10A and 10B are bar graph depicting number (FIG. 10A) anddistribution (FIG. 10B) of cells eluted from SCD membranes followingtheir use in SCD devices to treat septic subjects. The subjects weretreated with an F-40 SCD device in the presence of heparin (SCD-H); anF-40 SCD device in the presence of citrate (F-40 SCD-C); or an F-80A SCDdevice in the presence of citrate (F-80A SCD-C).

FIGS. 11A-B are graphical depictions of levels of serum myeloperoxidase(FIG. 11A) or systemic neutrophil activation, as measured by CD11b meanfluorescent intensity (FIG. 11B) shows hematocrit levels in subjectswith sepsis treated with an F-40 SCD device in the presence of heparin(SCD-H) or with an F-40 or F-80A SCD device in the presence of citrate(SCD-C).

FIGS. 12A-B are graphical depictions of release of IL-8 (FIG. 12A) andTNF-α (FIG. 12B) from peripheral blood mononuclear cells isolated fromsubjects after 6 hours of treatment for sepsis with an F-40 SCD devicein the presence of heparin (SCD-H); an F-40 SCD device in the presenceof citrate (F-40 SCD-C); or an F-80A SCD device in the presence ofcitrate (F-80A SCD-C). All values are expressed as the LPS-stimulated 6hour Septic Time Point Percent of LPS-stimulated 0 hour baseline, withp<0.05 for all SCD-C groups compared with the SCD-H group for IL-8 andTNF-α.

FIG. 13 is a photograph of lung sections incubated with primaryanti-CD11b antibody, followed by incubation with an anti-mouse IgGAlexafluor594 conjugate. Nuclei were counterstained with DAPI. The leftpanel is from a subject treated for sepsis with an F-40 SCD device inthe presence of heparin; the right panel is from a subject treated forsepsis with a SCD device in the presence of citrate. A significantdecrease in CD11b-labeled cells was observed in the lungs of thepatients whose regimen included citrate rather than heparin.

FIG. 14 is a bar graph depicting the number of CD11b-positive cellsdetected in non-septic subjects; septic subjects treated with an F-40SCD device in the presence of citrate (F-40 SCD-C); septic subjectstreated with an F-80A SCD device in the presence of citrate (F-80ASCD-C); or septic subjects treated with an F-40 SCD device in thepresence of heparin (F-40 SCD-H). Lung tissue leukocyte aggregation isexpressed as the number of CD11b positive cells/number of DAPI stainednucleic after IHC staining, with p<0.01 for all SCD-C groups compared tothe SCD-H group.

FIGS. 15A-C are graphical depictions of systemic white blood cell counts(FIG. 15A), systemic absolute neutrophil counts (FIG. 15B), and systemicimmature neutrophil counts (FIG. 15C) over time in septic subjectstreated with an F-40 SCD device in the presence of citrate (SCD-C,F-40), with an F-80A SCD device in the presence of citrate (SCD-C,F-80A), or with an F-40 SCD device in the presence of heparin (SCD-H).

FIG. 16 is a bar graph depicting the percentage of neutrophils that weredetected as positive for annexin V, as an assessment of the apoptoticpotential of the cells. Both systemic neutrophils and SCD-adherentneutrophils were measured following treatment of septic patients with anF-40 SCD (F-40 SCD-C) or an F-80A SCD (F-80A SCD-C) in the presence ofcitrate.

FIG. 17 is a bar graph depicting the relative numbers of leukocytesattaching to polysulfone in the presence of shear flow and in thepresence or absence of lipopolysaccharides (LPS) and/or citrate.

DETAILED DESCRIPTION

Cells associated with inflammation, such as leukocytes (or white bloodcells) and platelets, normally defend the body against infection andinjury. However, during many disease states and medical procedures,these cells can become activated, which in turn can produce undesirableimmune and inflammatory responses that can be fatal. It has beendiscovered that devices, referred to as selective cytopheretic devices,that extracorporeally sequester leukocytes and/or platelets and theninhibit their inflammatory actions can be useful in the prevention ortreatment of a variety of inflammatory conditions, in particularinflammatory conditions mediated or facilitated by activated leukocytesand/or platelets. U.S. Patent Publication No. US 2009/0060890 describesexemplary selective cytopheretic devices and their use in the preventionand/or treatment of inflammatory conditions. The selective cytophereticdevices described therein typically comprise a housing containing aplurality of fibers or planar sheets, the outer surfaces of whichcontact a body from the subject being treated. The outer surfaces of thehollow fibers or the planar sheets provide a solid support forselectively sequestering activated leukocytes and/or activated plateletspresent in the body fluid.

As used herein, the term “cytopheresis” or “selective cytopheresis”refers to the sequestration of certain cells, for example, leukocytes(e.g., activated leukocytes) or platelets (e.g., activated platelets)from a body fluid, for example, blood. The sequestered cells can bedeactivated and/or the release of the pro-inflammatory substance fromsuch cells can be inhibited. It should be understood that suchdeactivation and/or inhibition can occur before, during, and/or aftersequestration. In a specific embodiment, selective cytopheresis refersto the sequestration of leukocytes (e.g., activated leukocytes) and/orplatelets (e.g., activated platelets) from blood. The term “blood”refers to any aspect of blood, for example, whole blood, treated blood,filtered blood, or any liquid derived from blood, for example, serum orplasma.

The terms, “selective cytopheresis device,” “selective cytophereticdevice,” “selective cytopheresis inhibitory device,” and “SCD” eachrefer to a device that facilitates or is capable of facilitatingcytopheresis. Such a device can also facilitate deactivation and/orinhibit the release of pro-inflammatory substances from such cellsbefore, during, and/or after sequestration. The SCD includes one or moreSCD cartridges that facilitate selective cytopheresis. While thediscussion in the sections that follow generally describe sequestrationand inhibition and/or deactivation of a particular cell type (e.g.,leukocytes), it is understood that the same principles apply to thesequestration and inhibition and/or deactivation of other cell typesassociated with inflammation (e.g., platelets, such as activatedplatelets).

An “activated leukocyte” is understood to mean a leukocyte that, inresponse to a challenge, for example, when exposed to an endotoxin(e.g., lipopolysaccharide), has an enhanced ability to elicit an immuneresponse relative to a leukocyte that has not been challenged. Forexample, an activated neutrophil (PMN), is a neutrophil that, inresponse to a challenge, for example, when exposed to an endotoxin(e.g., lipopolysaccharide), has an enhanced ability to migrate,phagocytose, and produce an oxidative burst response relative to aneutrophil that has not been challenged. Activation can also bedetermined via an up-regulation of cell surface CD11b. An activatedmonocyte is a monocyte that, in response to a challenge, for example,when exposed to an endotoxin (e.g., lipopolysaccharide), has an enhancedability to release cytokines relative to a monocyte that has not beenchallenged. An “activated platelet” is understood to mean a plateletthat, in response to a challenge, for example, when exposed to anendotoxin (e.g., lipopolysaccharide), becomes adherent to otherplatelets, to leukocytes, and to certain proteins, for example,coagulation factors. Platelet activation can be quantified bydetermining the percentage of circulating monocytes that have plateletsadhered to their cell surface. Activated leukocytes also include primedleukocytes. For example, a primed neutrophil (PMN), is a neutrophilthat, in response to a challenge, for example, when exposed to anendotoxin (e.g., lipopolysaccharide), has an enhanced ability to undergoan oxidative burst response relative to a neutrophil that has not beenchallenged.

It has now been discovered that the choice of surface area of the solidsupport in a SCD cartridge capable of sequestering the leukocytes and/orthe platelets, and the inner volume (also referred to as the fillvolume) of the housing of the SCD cartridge that contains the solidsupport can have a profound effect on the efficacy of the SCD intreating an inflammatory condition. For example, the surface area of thesolid support should be sufficient to sequester a portion of theleukocytes and/or platelets to be effective but without sequestering toomany leukocytes and/or platelets. The sequestration of too manyleukocytes can result in leukocyte deficiency that in turn can result inlife-threatening leucopenia. The sequestration of too many neutrophilscan result in neutropenia, and the sequestration of too many plateletscan result in thrombocytopenia or bleeding diathesis. Furthermore, itcan be important to choose a housing with an appropriate inner volume(also referred to as the fill volume or the extracapillary space whenthe solid support is defined by hollow fibers) depending upon thesubject to be treated. For example, in the case of infants, children andseverely ill, hemodynamically unstable patients, it is important tochoose housings with lower fill volumes so that less body fluid needs tobe extracted from the subject to contact or bathe the solid support.Accordingly, the choice of a SCD cartridge having the appropriate ratioof active surface area of the solid support to the inner volume of theSCD cartridge housing containing the solid support can have a profoundeffect on the efficacy of treatment in a given patient. The age, weight,and infirmity of the subject can be important considerations whenchoosing a particular SCD cartridge.

Furthermore, although the invention is generally described herein withregard to blood and blood-based body fluids, the invention is applicableto any sample of a body fluid that can flow through an extracorporealcircuit, such as any body fluid from a subject that contains leukocytesand/or platelets. Exemplary extracorporeal circuits are described, forexample, in U.S. Pat. No. 6,561,997 and U.S. Patent Publication No. US2009/0060890. The terms “sample” and “specimen” are used in theirbroadest sense. On the one hand, they are meant to include a specimen orculture. On the other hand, they are meant to include both biologicaland environmental samples. Body fluids include, but not limited to,blood, serum, plasma, cerebrospinal fluid (CSF), lymphatic fluid,peritoneal fluid or ascites, pleural fluid, and saliva.

The following sections describe considerations in designing anappropriate SCD cartridge, and systems incorporating such a SCDcartridge for the treatment of a variety of inflammatory conditions.

1. Cartridge Considerations

Although the underlying principles for designing an appropriate SCD arediscussed in detail, it is understood that SCD cartridges useful in thepractice of the invention are not limited to the particular designconfigurations discussed herein.

In one aspect, the invention provides a SCD cartridge for treatingactivated leukocytes, activated platelets, or both activated leukocytesand activated platelets. The cartridge comprises a rigid housingdefining an inner volume (IV), a fluid inlet port and a fluid outletport. The inner volume is in fluid flow communication with both thefluid inlet port and the fluid outlet port. The inner volume is alsoreferred to herein as the fill volume, and also the extracapillary spaceor (ECS) in embodiments that contain hollow fibers. The inner volume canbe determined by sealing either the fluid inlet port or the fluid outletport of the rigid housing, filling the SCD cartridge with a liquid, forexample, water, via the unsealed port and then measuring the volume ofliquid that fills the housing to the top of the unsealed port. Inaddition, the cartridge comprises a solid support disposed within thehousing so at least a portion of the solid support isolated between thefluid inlet port and the fluid outlet port and defining a fluidcontacting surface with a surface area (SA) capable of sequestering anactivated leukocyte and/or an activated platelet, if present in abiological fluid entering the housing via the fluid inlet port. TheSA/IV ratio of the cartridge is greater than 150 cm⁻¹ (for example, theSA/IV ratio can be in the range from 150 cm⁻¹ to 1,500 cm⁻¹, from 300cm⁻¹ to 1,000 cm⁻¹, from 400 cm⁻¹ to 800 cm⁻¹, or from 200 cm⁻¹ to 600cm⁻¹) and the solid support (which can comprise a plurality of fibers orplanar sheets) is disposed within the housing at a packing density inthe range from 20% to 65% (for example, from 20% to 60%, or from 30% to60% or from 40% to 55%).

As used herein, the term “packing density” is understood to mean thepercentage of the total volume of the interior of a cartridge that isoccupied by the solid support. The volume V_(supp) occupied by the solidsupport is understood to include, for example, the aggregate volume ofall the fibers, sheets, or other elements defining the solid support. Ifthe solid support includes hollow elements, such as hollow fibers, thevolume occupied by the solid support is understood to include any hollowspaces (e.g., intracapillary spaces), as well as the volume occupied bythe material of the solid support. The total volume of the interior of acartridge is therefore the sum of the fill volume (IV) of the cartridgeand the volume occupied by the solid support. The packing density is thevolume occupied by the solid support “inner volume” divided by the totalvolume of the interior of the cartridge, and can be expressed asV_(supp)/(IV+V_(supp)), which can also be presented as a percentage. Forexample, if the volume of V_(supp) is 10 cm³, and the IV is 20 cm³, thepacking density is 0.3 or 30%.

In another aspect, the invention provides a cartridge for treatingactivated leukocytes, activated platelets, or both activated leukocytesand activated platelets. The cartridge comprises (a) a rigid housingdefining an inner volume (IV), a fluid inlet port and a fluid outletport, wherein the inner volume is in fluid flow communication with thefluid inlet port and the fluid outlet port; and (b) a solid supportdisposed within the housing and defining a fluid contacting surface witha surface area (SA) capable of sequestering an activated leukocyteand/or an activated platelet if present in a body fluid entering thehousing via the fluid inlet port, wherein the SA is greater than 2.6 m²(for example, from 3.0 m² to 10.0 m² or from 3.0 m² to 5.0 m²).

In another aspect, the invention provides a cartridge for treatingactivated leukocytes, activated platelets, or both activated leukocytesand activated platelets. The cartridge comprises (a) a rigid housingdefining an inner volume (IV), a fluid inlet port and a fluid outletport, wherein the inner volume is in fluid flow communication with thefluid inlet port and the fluid outlet port; and (b) a solid supportcomprising a plurality of solid fibers disposed within the housing, thesolid support defining a fluid contacting surface with a surface area(SA) capable of sequestering an activated leukocyte and/or an activatedplatelet if present in a body fluid entering the housing via the fluidinlet port, wherein the SA/IV ratio is greater than 25 cm⁻¹ (forexample, greater than 80 cm⁻¹, greater than 150 cm⁻¹, or in the rangefrom 150 cm⁻¹ to 1,500 cm⁻¹, in the range from 80 cm⁻¹ to 800 cm⁻¹, inthe range from 25 cm⁻¹ to 800 cm⁻¹).

In another aspect, the invention provides a method of using a cartridge(i) for processing an activated leukocyte, activated platelet or acombination thereof, or (ii) for treating a subject at risk ofdeveloping or having an inflammatory condition. The method comprisesproviding a cartridge comprising (i) a rigid housing defining an innervolume (IV), a fluid inlet port and a fluid outlet port; and (ii) asolid support disposed within the housing so at least a portion of thesolid support isolated between the fluid inlet port and the fluid outletport and defining a fluid contacting surface with a surface area (SA)capable of sequestering an activated leukocyte, if present in abiological fluid entering the housing via the fluid inlet port. In themethod, the SA/IV ratio of the cartridge is greater than 80 cm⁻¹. Themethod further comprises introducing a body fluid from a subject intothe housing via the fluid inlet port under conditions that permitsequestration of an activated leukocyte and/or an activated platelet onthe fluid contacting surface of the solid support.

FIG. 1A shows a schematic, cross-sectional representation of anexemplary SCD cartridge 100. SCD cartridge 100 comprises a housing 110that defines an inner volume or fill volume 112, a fluid inlet port 114,a fluid contacting inner surface 116, and a fluid outlet port 118. Thefluid inlet port 114, inner volume (or fill volume) 112, and fluidoutlet port 118 are in fluid flow communication with one another. Asshown, the fluid inlet port 114 and the fluid outlet port 118 aredisposed on the same side of the housing (i.e., are ipsilateral). Inthis embodiment, the housing further comprises a solid support 120defined by the exterior surface(s) of one or more hollow fibers. FIG. 1Ashows three hollow fibers. In this embodiment, the interior of thehollow fibers 120 together define an intracapillary space (“ICS”) 122,and the volume disposed between the fluid contacting inner surface 116of the housing and the exterior surface of the hollow fibers 120together define the inner volume 112, which is also referred to as theextracapillary space (“ECS”). Depending upon the particular embodiment,a fluid, for example, an ultrafiltrate, can be introduced into ICS 122of the SCD 100 via an ICS inlet 126 which can then pass into or throughICS 122 and, if desired, exit housing 110 via ICS outlet 128. In certainembodiments, however, the ICS inlet 126 can be blocked or otherwisecapped with end cap 130 and/or ICS outlet 128 can be blocked orotherwise capped with end cap 132. In this embodiment, at least aportion of solid support 120 is disposed within housing 110 betweenfluid inlet port 114 and fluid exit port 118.

During operation of this SCD cartridge, the fluid sample of interest isintroduced into housing 110 via fluid inlet 114 into inner volume (orECS) 112. The fluid then passes along the surface of solid support 120(along the exterior surface of the hollow fibers) in a planesubstantially parallel to the plane of the solid support 120, and thenexits inner volume (or ECS) 112 via fluid exit port 118. During passagealong solid support 120, activated leukocytes and/or platelets aresequestered and optionally deactivated. As a result, during operation,cells (for example, leukocytes) from the body fluid (for example, blood)associate with a particular region within the passageway defined by thecartridge housing, specifically, with the exterior surface of the hollowfibers. Accordingly, in certain embodiments, a passageway regionconfigured to sequester leukocytes may include a porous membrane thatpermits smaller molecules to pass therethrough but forces largermolecules and/or cells to flow along the membrane. Moreover, in certainembodiments, the passageway region configured to sequester leukocytes isbounded by a surface of a housing and is bounded by, and may include,the exterior surface or surfaces of hollow fibers configured such thatthe biological sample (e.g., a subject's blood or filtered blood) flowsover these surfaces (i.e., over the hollow fibers). See, for example,FIG. 1. The hollow fibers may be porous, semi-porous, or non-porous anda different fluid (e.g., ultrafiltrate) may optionally flow or bepresent within the hollow fibers. The fibers can be formed from anysuitable material described herein.

FIG. 1B shows a schematic, cross-sectional representation of anotherexemplary SCD cartridge 100. SCD cartridge 100 comprises a housing 110that defines an inner volume 112, a fluid inlet port 114, a fluidcontacting inner surface 116, and a fluid outlet port 118. The fluidinlet port 114 and the fluid outlet port 118 are disposed on the sameside of the housing (i.e., are ipsilateral). In this embodiment, thehousing further comprises a solid support 120 defined by the exteriorsurfaces of a solid substrate, which can be, for example, one or more (aplurality of) solid fibers or one or more (a plurality of) planarsupports (for example, a flat membrane). In this FIG. 1B, which shows across-sectional representation of a SCD cartridge, the solid support isdefined by three solid fibers or three sheets of a planar support member(for example, a planar membrane). However, it is understood that aplurality of solid fibers or planar support members may together definethe solid support. The volume disposed between the fluid contactinginner surface 118 of the housing and the exterior surface of the solidfiber(s) or the planar support member(s) together define the innervolume (or fill volume) 112. In contrast to the embodiment shown in FIG.1A, the solid fibers or planar support members, because they are nothollow, do not define an ICS. In this embodiment, at least a portion ofsolid support 120 is disposed within housing 110 between fluid inletport 114 and fluid exit port 118.

During operation of this SCD cartridge, the fluid sample of interest isintroduced into housing 110 via fluid inlet part 114 into the innervolume (ECS) 112. The fluid then passes along the surface of solidsupport 120 (along the exterior surface of the solid fibers or planarsupport, or a combination of one or more solid fibers with one or moreplanar supports) in a plane substantially parallel to the plane of thesolid support 120 and then exits inner volume 112 via fluid exit port118. During movement of the body fluid along solid support 120,activated leukocytes and/or platelets are sequestered.

The SCD cartridges shown in FIGS. 1C and 1D are similar to the SCDcartridge shown in FIG. 1B. In FIG. 1C, the fluid inlet port 114 andfluid outlet port 118 are located at opposite sides of the housing(i.e., are contralateral). In FIG. 1C, housing 110 has a first end and asecond end opposite the first end, where fluid inlet port 114 isconfigured to permit fluid flow through first end and fluid outlet port118 is configured to permit fluid flow through the second end.

The SCD cartridge can be configured in any of a variety of ways tosequester cells, for example, leukocytes. As will be discussed in moredetail below, the SCD cartridge preferably is designed with a particularsubject and indication in mind. For example, the surface area of thesolid support should be sufficient to sequester a portion of theactivated leukocytes and/or activated platelets to be effective withoutsequestering too many leukocytes, which potentially can causelife-threatening leukopenia, neutropenia, or too many plateletsresulting in thrombocytopenia, or bleeding diathesis. Furthermore, itcan be important to choose a housing with an appropriate inner volumedepending upon the subject to be treated. For example, in the case ofinfants, children and severely ill, hemodynamically unstable patients,it is important to choose housings with lower fill volumes so that lessbody fluid needs to be extracted from the subject in order to contact orbathe the solid support. It is understood that the SCD cartridge can beconfigured in any of a variety of ways to sequester cells, for example,leukocytes, and to have the appropriate inner volume.

The solid support can be defined by any number of surfaces, for example,1, 2, 3, 4, 5, 10, 20, 50, 100, or more different surfaces. Dependingupon the subject and the indication to be treated, the surface area ofthe solid support is greater than about 0.09 m², is greater than about0.1 m², is greater than about 0.2 m², greater than 0.4 m², greater than0.6 m², greater than 0.8 m², greater than 1.0 m², greater than 1.5 m²,or greater than 2.0 m².

The surface area of the solid support can be in the range of 0.1 m² to10.0 m², or 0.1 m² to 5.0 m². More specifically, the surface area of thesolid support can be in the range from 0.1 m² to 0.4 m², from 0.4 m² to0.8 m², from 0.8 m² to 1.2 m², from 1.2 m² to 1.6 m², from 1.6 m² to 2.0m², from 2.0 m² to 2.4 m², from 2.4 m² to 2.8 m², from 2.8 m² to 3.2 m²,from 3.2 m² to 3.6 m², from 3.6 m² to 4.0 m², from 4.0 m² to 4.4 m²,from 4.4 m² to 4.8 m², from 4.8 m² to 5.2 m², from 5.2 m² to 5.6 m²,from 5.6 m² to 6.0 m², from 6.0 m² to 6.4 m², from 6.4 m² to 6.8 m²,from 6.8 m² to 7.2 m², from 7.2 m² to 7.6 m², from 7.6 m² to 8.0 m²,from 8.0 m² to 8.4 m², from 8.4 m² to 8.8 m², from 8.8 m² to 9.2 m²,from 9.2 m² to 9.6 m², or from 9.6 m² to 10.0 m²

As a general guiding principle, it is contemplated that when treatingsubjects having a body weight less than 50 kg the surface area of thesolid support preferably should be in the range of the from 0.4 m² to0.8 m², when treating subjects having a body weight greater than 50 kgbut less than 100 kg, the surface area of the solid support preferablyshould be in the range of the from 0.8 m² to 1.6 m², and when treatingsubjects having a body weight greater than 100 kg the surface area ofthe solid support preferably should be in the range of the from 1.6 m²to 5.0 m². It is understood, however, that when therapy is initiated, ifthe patient shows symptoms of developing leukopenia and/or neutropenia,the SCD cartridge can be replaced with a cartridge with a lower surfacearea to avoid sequestering too many leukocytes and/or platelets.

The housing of the cartridge is not limited to a particular set ofdimensions (e.g., length, width, weight, or other dimension) in order toachieve a particular fill volume. Depending upon the subject and theindication to be treated, the IV can be less than 300 cm³, or less than150 cm³, or less than 100 cm³, or less than 80 cm³, or less than 60 cm³,or less than 40 cm³, or less than 20 cm³. In certain embodiments, the IVis in the range of from 10 cm³ to 150 cm³, 75 cm³ to 150 cm³, 20 cm³ to80 cm³, or 15 cm³ to 120 cm³. In the case of infants, children, andseverely ill, hemodynamically unstable patients, the inner volume can beless than 40 cm³, for example, in the range from 5 cm³ to 50 cm³, from 1cm³ to 20 cm³ or from 5 cm³ to 30 cm³.

In certain embodiments, the SA/IV ratio is in the range from 25 cm⁻¹ to2,000 cm⁻¹, 25 cm⁻¹ to 1,750 cm⁻¹, 25 cm⁻¹ to 1,500 cm⁻¹, 25 cm⁻¹ to1,250 cm⁻¹, 25 cm⁻¹ to 1,000 cm⁻¹, 25 cm⁻¹ to 800 cm⁻¹, 80 cm⁻¹ to 2,000cm⁻¹, 80 cm⁻¹ to 1,750 cm⁻¹, 80 cm⁻¹ to 1,500 cm⁻¹, 80 cm⁻¹ to 1,250cm⁻¹, 80 cm⁻¹ to 1,000 cm⁻¹, 80 cm⁻¹ to 800 cm⁻¹, 100 cm⁻¹ to 2,000cm⁻¹, 100 cm⁻¹ to 2,000 cm⁻¹, 100 cm⁻¹ to 1,750 cm⁻¹, 100 cm⁻¹ to 1,500cm⁻¹, 100 cm⁻¹ to 1,250 cm⁻¹, 100 cm⁻¹ to 1,000 cm⁻¹, 100 cm⁻¹ to 800cm⁻¹, from 125 cm⁻¹ to 2,000 cm⁻¹, 125 cm⁻¹ to 1,750 cm⁻¹, 125 cm⁻¹ to1,500 cm⁻¹, 125 cm⁻¹ to 1,250 cm⁻¹, 125 cm⁻¹ to 1,000 cm⁻¹, or 125 cm⁻¹to 800 cm⁻¹, 150 cm⁻¹ to 2,000 cm⁻¹, 150 cm⁻¹ to 1,750 cm⁻¹, 150 cm⁻¹ to1,500 cm⁻¹, 150 cm⁻¹ to 1,250 cm⁻¹, 150 cm⁻¹ to 1,000 cm⁻¹, 150 cm⁻¹ to800 cm⁻¹, 200 cm⁻¹ to 2,000 cm⁻¹, 200 cm⁻¹ to 1,750 cm⁻¹, 200 cm⁻¹ to1,500 cm⁻¹, 200 cm⁻¹ to 1,250 cm⁻¹, 200 cm⁻¹ to 1,000 cm⁻¹, 200 cm⁻¹ to800 cm⁻¹, 200 cm⁻¹ to 600 cm⁻¹, from 300 cm⁻¹ to 2,000 cm⁻¹, from 300cm⁻¹ to 2,000 cm⁻¹, from 300 cm⁻¹ to 1,750 cm⁻¹, from 300 cm⁻¹ to 1,500cm⁻¹, from 300 cm⁻¹ to 1,250 cm⁻¹, from 300 cm⁻¹ to 1,000 cm⁻¹, 300 cm⁻¹to 800 cm⁻¹, from 400 cm⁻¹ to 1,200 cm⁻¹, from 400 cm⁻¹ to 1,000 cm⁻¹,from 400 cm⁻¹ to 800 cm⁻¹, from 500 cm⁻¹ to 1,200 cm⁻¹, from 500 cm⁻¹ to1000 cm⁻¹, or from 500 cm⁻¹ to 800 cm⁻¹.

The housing of the cartridge can be fabricated from a variety ofmaterials, but the material that defines that fluid contacting surfacein the inner volume should be biocompatible. The SCD cartridge can beconstructed from a variety of materials including, metals such astitanium, or stainless steel with or without surface coatings ofrefractory metals including titanium, tantalum, or niobium; ceramicssuch as alumina, silica, or zirconia; or polymers, such aspolyvinylchloride, polyethylene, or polycarbonate.

The solid support can be defined by flat surfaces (e.g., sheets), curvedsurfaces (e.g., hollow tubes, hollow fibers, solid tubes, and solidfibers), patterned surfaces (e.g., z-folded sheets or dimpled surfaces),irregularly-shaped surfaces, or other configurations to sequester cells.It is understood that the solid support can be defined by a variety ofmaterials, which can include, for example, hollow fibers, solid fibers,planar support members (for example, planar membranes) or a combinationof two or more of the foregoing (for example, a combination of hollowand solid fibers, a combination of hollow fibers and planar supportmembers, or a combination of solid fibers and planar support members).In certain embodiments, the solid support is substantially parallel tothe plane of fluid flow within the SCD cartridge from fluid inlet port114 to the fluid exit port.

Depending upon the embodiment, the solid support can comprise amembrane. The term “membrane” refers to a surface capable of receiving afluid on both sides of the surface, or a fluid on one side and gas onthe other side of the surface. A membrane can be porous (e.g.,selectively porous or semi-porous) such that it is capable of fluid orgas flow therethrough. It is understood that the term “porous” as usedherein to describe a surface or membrane includes generally porous,selectively porous and/or semi-porous surfaces or membranes. Moreover,additional surfaces that can facilitate leukocyte sequestration, such asparticle (e.g., bead) surfaces, surfaces of one or more projections intothe passageway, or surfaces of one or more membranes exposed to theflowing biological sample.

It is understood that the solid support is not limited to a particulartype, kind or size, and may be made of any appropriate material;however, the material should be biocompatible. For example, a surface ofthe solid support may be any biocompatible polymer comprising one ormore of nylon, polyethylene, polyurethane, polyethylene terephthalate(PET), polytetrafluoroethylene (PTFE), CUPROPHAN (a celluloseregenerated by means of the cuprammonium process, available from Enka),HEMOPHAN (a modified CUPROPHAN with improved biocompatibility, availablefrom Enka), CUPRAMMONIUM RAYON (a variety of CUPROPHAN, available fromAsahi), BIOMEMBRANE (cuprammonium rayon available from Asahi),saponified cellulose acetate (such as fibers available from Teijin or CDMedical), cellulose acetate (such as fibers available from ToyoboNipro), cellulose (such as that are regenerated by the modifiedcupramonium process or by means of the viscose process, available fromTerumo or Textikombinat (Pima, GDR) respectively), polyacrylonitrile(PAN), polysulfone, polyethersulfone, polyarylethersulfone, acryliccopolymers (such as acrylonitrile-NA-methallyl-sulfonate copolymer,available from Hospal), polycarbonate copolymer (such as GAMBRONE, afiber available from Gambro), polymethylmethacrylate copolymers (such asfibers available from Toray), and ethylene vinyl copolymer (such asEVAL, a ethylene-vinyl alcohol copolymer available from Kuraray).Alternatively, a surface may be nylon mesh, cotton mesh, or woven fiber.The surface can have a constant thickness or an irregular thickness. Insome embodiments, surfaces may include silicon, for example, siliconnanofabricated membranes (see, e.g., U.S. Patent Publication No.2004/0124147). In some embodiments, surfaces may include polysulfonefibers. Other suitable biocompatible fibers are known in the art, forexample, in Salem and Mujais (1993) DIALYSIS THERAPY 2D ED., Ch. 5:Dialyzers, Eds. Nissensen and Fine, Hanley & Belfus, Inc., Philadelphia,Pa.

Any technique or combination of techniques that facilitatessequestration of the leukocytes can be used, including, for example,biological, chemical, mechanical and/or physical techniques. In someembodiments, biological or chemical techniques for sequestration can beused. Such techniques include using tissues, cells, biomolecules (forexample, proteins or nucleic acids), or small molecules to sequesterleukocytes. In one embodiment, for example, the fluid contacting supportof the solid support in the ECS can further comprise a cell adhesionmolecule attached thereto to facilitate sequestration.

For example, when a leukocyte is activated, selectins are produced bythe leukocyte. This altered selectin production can facilitate bindingbetween the leukocyte and other leukocytes. In turn, the binding betweenleukocytes can increase selectin production in the additionally boundleukocytes, yielding exponential binding of leukocytes. Thus, selectinsmay be useful to enhance sequestration. Proteins, protein complexes,and/or protein components known to bind leukocytes include CD11a, CD11b,CD11c, CD18, CD29, CD34, CD44, CD49d, CD54, podocalyxin, endomucin,glycosaminoglycan cell adhesion molecule-1 (GlyCAM-1), mucosal addressincell adhesion molecule-1 (MAdCAM-1), E-selectin, L-selectin, P-selectin,cutaneous lymphocyte antigen (CLA), P-selectin glycoprotein ligand 1(PSGL-1), leukocyte functional antigen-1 (LFA-1), Mac-1, leukocytesurface antigen p150,95, leukocyte integrin CR4, very late antigen-4(VLA-4), lymphocyte Peyers patch adhesion molecule-1 (LPAM-1),intracellular adhesion molecule-1 (ICAM-1), intracellular adhesionmolecule-2 (ICAM-2), intracellular adhesion molecule-3 (ICAM-3),inactivated C3b (C3bi), fibrinogen, fibronectin, peripheral lymph nodeaddressin (PNAd), endothelial vascular adhesion protein 1 (VAP-1),fractalkine, CCL19, CCL21, CCL25, and CCL27. Other large molecules knownto bind leukocytes include hyaluronic acid, glycosaminoglycans (GAGs),and fucosylated oligosaccharides and their precursors. In certainembodiments, small molecules or adherents used to sequester a leukocytecan include, but are not limited to, peptides, such as peptidescomprising the amino acid sequence arginine-glycine-aspartic acid (RGD),and molecules comprising sialic acid. Accordingly, any of thesematerials can be used to enhance sequestration.

During use, any of these biological or chemical materials may be boundto the fluid contacting surface of the solid support and/or the fluidcontacting surface of the cartridge housing to facilitate or enhancesequestration. Alternatively, or in combination, any of these materialsmay be used with other additional techniques to facilitatesequestration. For example, materials may be used to bind leukocytes insolution, causing them to agglomerate and to increase their overall sizerelative to the size of a single leukocyte. The agglomerated leukocytesthen can be captured with a membrane having a particular pore size.

It should be understood that the sequestration techniques describedherein also can apply to platelets. In the case of platelets, similarbiological, chemical, mechanical and/or physical techniques as describedabove may be used to sequester platelets. In certain embodiments, agentsused to sequester platelets include one or more of glycoprotein Ibα(GPIbα), glycoprotein IIb (GPIIb), glycoprotein IIIa (GPIIIa), CD41,CD61, von Willebrand Factor, β₂-integrin macrophage antigen-1, selectinssuch as P-selectin, and a cell-adhesion molecule.

In addition, sequestration can also be facilitated and/or enhanced bythe control of certain mechanical forces that occur within the SCDcartridge. For example, leukocytes may be sequestered on one or moresurfaces of (or in) a passageway or passageway region (e.g., the outsideof a porous hollow fiber) by utilizing a flow rate and deviceconfiguration that minimizes shear force between the leukocytes and thesurface(s), allowing the leukocytes to associate with the surface(s).For example, the housing is configured to create a low shear forceenvironment to permit the cells of interest, for example, leukocytes,platelets, etc, to be sequestered on the solid support as body fluidtraverses the inner volume.

More specifically, the cartridge is configured to facilitate shearforces between the flowing cells (for example, leukocytes or platelets)and the sequestration surface(s) less than 1000 dynes/cm², less than 500dynes/cm², less than 100 dynes/cm², less than 80 dynes/cm², less than 60dynes/cm², less than 40 dynes/cm², less than 20 dynes/cm², less than 10dynes/cm², or less than 5 dynes/cm² when a biological fluid enters thecartridge housing through fluid inlet port 114 and exits the cartridgehousing through the fluid outlet port 118, for example, at a flow ratein the range of 10 mL (cm³)/minute to about 8,000 mL (cm³)/minute orfrom 50 mL/minute to about 8,000 mL/minute (for example, 1,000cm³/minute). As a result, the fluid inlet port 114 and the fluid outletport 118 are dimensioned to permit a flow rate through the housing in arange from 10 mL/minute to 8,000 mL/minute or from 50 mL/minute to 8,000mL/minute. For example, when treating certain inflammatory disorders,for example, inflammatory responses during cardiopulmary bypass, it isunderstood that treating large flow rates can be tolerated, for example,up to 7000 mL/minute. Similarly, when sepsis, it is understood that flowrates up to, for example, 1000 mL/minute can be tolerated. That said,when treating inflammatory responses associated with other indications,for example, acute renal failure and chronic renal failure, slower flowrates should be used, for example, less than about 500 mL/minute, fromabout 100 mL/minute to about 500 mL/minute, and from about 200 mL/minuteto about 500 mL/minute. As a result, the inlet port 114 and the outletport 118 are dimensioned to permit a desired volume of body fluid topass through the SCD cartridge housing in a given amount of time. It isunderstood that the fluid inlet port 114 and the fluid outlet port 118each have an internal diameter of no less than 0.1 cm to 2 cm, or 0.2 cmto 1 cm, or have a cross-sectional surface area of no less than 0.01cm², no less than 0.1 cm², no less than 0.2 cm², no less than 0.4 cm²,no less than 0.6 cm², no less than 0.8 cm², no less than 1.0 cm², noless than 2.0 cm², or no less than 3.0 cm². In certain embodiments, theinlet port, the outlet port, or both the inlet and outlet ports have across-sectional surface area of 0.01 cm² to 1 cm². The distance betweenthe fluid inlet or fluid outlet to the nearest end of the housing(distance A), can be such that A divided by the length of the housing isbetween 0.01 and 0.25. It is also understood that the plane of the inletand/or outlet port can range from 5 degrees to 90 degrees (i.e., isperpendicular) to the plane defined by the longest dimension (usuallythe length) of the housing.

In certain embodiments, the fluid inlet port 114 and the fluid outletport 118 are both disposed on one side of the housing 116, for example,as shown in FIGS. 1A and 1B. Alternatively, as shown in FIG. 1C, thefluid inlet port 114 and the fluid outlet port 116 can be disposed onopposite sides of the housing 116. Other orientations of the fluid inletport 114 and the fluid outlet port 116 are also envisioned. For example,if the housing comprises a first end and a second end opposite the firstend, the fluid inlet port can be configured to permit fluid flow throughthe first end and/or the fluid outlet port can be configured to permitfluid flow through the second end. One such orientation is depicted inFIG. 1D, in which fluid inlet port 114 permits fluid flow through theleft end of housing 116, and fluid outlet port 118 permits the fluid toexit through the right end of housing 116.

It is understood that the size and shape of the housing of the SCDcartridge may be designed to provide the appropriate fill volume and tominimize turbulence when a fluid is passed through the SCD cartridge.Furthermore, it is understood that the size, shape and composition ofthe solid support located within the SCD cartridge may be designed toprovide the appropriate surface area and to minimize turbulence when afluid is passed through the SCD cartridge.

By way of example, when solid fibers are used to create the solidsupport in the cartridge, if a cartridge having a total surface area of1.8 m² to 2.5 m² is desired, the cartridge can be designed to containabout 43,000 fibers when the fiber length is 26 cm and the fiberdiameter is 50 μm, or about 22,000 fibers when the fiber length is 26 cmand the fiber diameter is 100 μm, or about 11,000 fibers when the fiberlength is 26 cm and the fiber diameter is 200 μm, or about 43,000 fiberswhen the fiber length is 13 cm and the fiber diameter is 100 μm, orabout 22,000 fibers when the fiber length is 13 cm and the fiberdiameter is 200 μm. Alternatively, if the cartridge having a totalsurface area of 3.6 m² to 5.0 m² is desired, the cartridge can bedesigned to contain about 87,000 fibers when the fiber length is 26 cmand the fiber diameter is 50 μm, or about 43,000 fibers when the fiberlength is 26 cm and the fiber diameter is 100 μm, or about 87,000 fiberswhen the fiber length is 13 cm and the fiber diameter is 100 μm.

In contrast, and by way of example, when planar support members are usedto create the solid support, if a cartridge with a total surface area of1.8 m² to 2.5 m² is desired, the cartridge can contain, for example, aplurality of sheets having an average thickness of 50 μm and an averagewidth of 5 cm (for example, about 115 sheets of a membrane about 12 cmin length, or 63 sheets of membrane about 26 cm in length). In contrast,if a cartridge with a total surface area of 3.6 m² 5.0 m² is desired,the cartridge can contain about 125 sheets of membrane having an averagethickness of 50 μm, an average width of 5 cm, and average length of 26cm. The sheets may be placed within the cartridge such that, in certainembodiments, the spacing between the sheets is about 50 μm or 100 μm.

In certain embodiments, the cartridge can be designed such that thesolid support (for example, the fibers or planar supports thatconstitute the solid support) is disposed within the housing at apacking density from 20% to 65%, 20% to 60%, from 30% to 60%, or from40% to 55%. The packing density should be chosen to minimize the risk ofclotting when blood is passed across the solid support disposed withinthe IV of the housing.

When hollow fibers are used in the SCD cartridge, the SA/IV ratiopreferably is at least 80 cm⁻¹ or more. Exemplary SCD cartridges with aSA/IV ratio greater than 80 cm⁻¹ include the F-50, F-60, F-70 and F-80Acartridge, which are available commercially from Fresenius Medical CareNorth America, Waltham, Mass., U.S.A.) or Renaflow cartridges (PSHseries) from Baxter (Deerfield, Ill., U.S.A.). These cartridges havebeen approved by the USFDA for use in acute and chronic hemodialysis.The F-80A cartridge, for example, has a solid support (defined by theexterior surfaces in a bundle of hollow fibers) with a surface areacapable of sequestering leukocytes and/or platelets of about 2.5 m², hasan inner volume of about 250 mL, and a SA/IV ratio of about 100.

In certain embodiments, exemplary cartridges can have the features setforth in Table 1.

TABLE 1 ECS SA ECS SA ECS Fill Device (m²) (cm²) (cm³) SA/V (cm⁻¹) 10.98 9800 130 75 2 2.5 25000 250 100 3 1.25 12500 125 100 4 2.5 25000125 200 5 2.5 25000 109 230 6 2.5 25000 94 267 7 5 50000 93 536 8 550000 125 400 9 6.7 67000 125 537 10 10 100000 125 800

In certain embodiments, in particular, for pediatric uses, exemplarycartridges can have the features set forth in Table 2.

TABLE 2 ECS SA ECS SA ECS Fill SA/V Device (m²) (cm²) (cm³) (cm⁻¹) 1 -1.5 cm case; 200 μm fibers 0.17 1700 9 185 2 - 1.5 cm case; 100 μmfibers 0.35 3500 9 392 3 - 1.5 cm case; 75 μm fibers 0.47 4700 9 530 4 -1.5 cm case; 50 μm fibers 0.70 7000 9 784 5 - 2.5 cm case; 200 μm fibers0.49 4900 25 199 6 - 2.5 cm case; 100 μm fibers 0.98 9800 25 399 7 - 2.5cm case; 75 μm fibers 1.30 13000 25 526 8 - 2.5 cm case; 50 μm fibers1.96 19600 25 797

In certain embodiments, a system can achieve sequestration by subjectingthe leukocytes, platelets or cells of interest to a series ofcartridges, for example, 2, 3, 4, 5, 6, 7, 8, 9, 10, or more cartridges(e.g., hollow fiber cartridges), each comprising one or moresequestration passageways, or passageway regions, so as to increase thelength of the region configured to sequester the leukocytes and theresidence time of the leukocytes therein. In any of the aforementionedembodiments, the devices are configured to accomplish sequestration ofleukocytes in a manner permitting inhibition of release of apro-inflammatory substance from a leukocyte and/or deactivation of aleukocyte before, during, or after sequestering. Inhibition of releaseof a pro-inflammatory substance from a leukocyte and/or deactivation ofa leukocyte can be achieved both during sequestration and duringtransport through a passageway, passageway region, or entire system ofthe present invention.

In some embodiments, the SCD cartridges or fluid circuits incorporatingthe SCD cartridges are configured to sequester the leukocytes for anydesired amount of time, for example, from 1 to 59 seconds, from 1 to 59minutes, from 1 to 24 hours, from 1 to 7 days, one or more weeks, one ormore months, or one year or more. In some embodiments, the devices areconfigured to sequester leukocytes for an amount of time sufficient topermit the subsequent inhibition of release of a pro-inflammatorysubstance from the leukocytes and/or deactivation the leukocytes. Incertain embodiments, leukocytes and/or platelets are sequestered withinthe SCD cartridge for at a time (e.g., at least 1, 2, 3, 4, 5, 6, 7, 8,9, 10, 15 minutes or at least an hour) sufficient to deactivate theleukocyte and/or inhibit the release of a pro-inflammatory substance.

It is understood that the SCD cartridge, once fabricated should besterilized prior to use. Sterility can be achieved through exposure toone or more sterilizing agents, separately or in combination, such ashigh temperature, high pressure, radiation, or chemical agents such asethylene oxide, for example. The SCD cartridge preferably is sterilizedonce it has been packaged, for example, after it has been hermeticallysealed within an appropriate container (i.e., the cartridge isterminally sterilized). The sterilization process preferably achieves asterility assurance level (SAL) of 10⁻³ or less; i.e. the probability ofany given unit being nonsterile after the process is no more than 1 in10³. More preferably, the sterilization process achieves an SAL of nomore than 10⁻⁴, no more than 10⁻⁵, or no more than 10⁻⁶.

2. System Configurations

It is understood that the SCD cartridges can be used in a variety ofdifferent fluid circuits depending upon the indication to be treated.See, for example, U.S. Patent Publication No. 2009/0060890 A1.

In some embodiments, fluid circuits incorporating the SCD cartridgeoptionally can also perform other blood treatments. For example, fluidcircuits optionally can further include additional devices that canfilter, oxygenate, warm, or otherwise treat the blood before or afterthe blood enters the SCD cartridge. Moreover, the SCD cartridge and/oradditional devices in a system can include more than one component fortreating blood in other or complementary ways, for example, porousfilters, oxygen pumps, and/or xenographic or allographic cells (forexample, xenographic or allographic renal cells such as renal tubulecells). In certain embodiments, the SCD cartridge is free of suchadditional components. For example, a SCD cartridge may be free of cellssuch as xenographic or allographic cells (e.g., xenographic orallographic renal cells). These basic principles are described in moredetail below.

The fluid circuits are configured to accomplish selective cytopheresis.In basic form, the system includes a SCD cartridge, a fluid connectionfor blood to flow from a blood source (for example, a subject, such as apatient) to the SCD cartridge, and a fluid connection for treated bloodto flow from the SCD cartridge to a receptacle (for example, back to thesubject). The SCD cartridge acts to sequester cells, for example,leukocytes, such as activated leukocytes, and facilitate inhibition ofrelease of a pro-inflammatory substance from the leukocytes and/ordeactivate the leukocytes. Sequestration of leukocytes can be achievedusing the SCD cartridges described hereinabove. Inhibition of therelease of a pro-inflammatory substance from the leukocytes and/ordeactivation of the leukocytes can be achieved by any techniquedescribed in Section 3 below.

The leukocytes may become activated within the subject as result of aprimary patient condition or secondary to other types of medicalintervention, for example, during passage through a hemofilter (forexample, as described hereinbelow, with reference to FIGS. 2C and 2D).The activated leukocytes then enter a SCD cartridge wherein theactivated leukocytes are sequestered. In the case of the circuit in FIG.2D, replacement fluid equal to the volume of the ultrafiltrate producedoptionally is provided to the subject.

In other words, in the SCD cartridge, the activated leukocytes from theblood are sequestered, for example, by temporarily adhering to one ormore surfaces inside the cartridge. Sequestration of the leukocytes canbe achieved by a variety of approaches, for example, by association withmolecules in a passageway or passageway region in the cartridge thatbind leukocytes, for example, activated leukocytes, or by setting bloodflow within the device to provide low shear stress on leukocytes,allowing them to associate with one or more surfaces inside the SCDcartridge. These sequestered leukocytes then are exposed to an agent,for example, citrate, to deactivate the leukocytes or inhibit theirrelease of pro-inflammatory substances. The cartridges can also be usedto sequester and deactivate other cell types, such as platelets.

It is believed that calcium chelators, for example, citrate, lead to alow Ca, environment in the cartridge thereby inhibiting release of apro-inflammatory substance from the leukocytes and/or deactivating theleukocytes. Pro-inflammatory substances may include destructive enzymesand/or cytokines from the leukocytes. This inhibition and/ordeactivation leads to an amelioration of the inflammatory state of theleukocytes. In this way, the SCD cartridge sequesters leukocytes, forexample, neutrophils and monocytes, and inhibits release of apro-inflammatory substance from the leukocytes and/or deactivates theleukocytes, for example, with citrate and/or a low-Ca, environment. Thesequestration and inhibition and/or deactivation of platelets can beachieved in a similar fashion.

It has been demonstrated that the addition of a calcium chelator, e.g.citrate, to a device of the present invention including a housingcontaining hollow fibers that sequester leukocytes had the unexpectedresult of improving a subject's innate immunologic system. Accordingly,it is contemplated that the SCD cartridges of the present invention cantreat or prevent a variety of inflammatory conditions (either as primarydisease states or as a result of medical intervention) by directlytreating a subject's blood that includes leukocytes (e.g., activatedleukocytes) or platelets (e.g., activated platelets). Followingtreatment, the blood is returned to the subject.

2.A. Single Device System

As mentioned, a system can contain a SCD cartridge to accomplishselective cytopheresis and, optionally, other blood treatments withoutadditional treatment devices in the system (see FIGS. 2A-2B). In oneembodiment, such a SCD cartridge is shown schematically in FIG. 1A.During operation, leukocytes and/or platelets are sequestered within theSCD cartridge, for example, at the external surface of the hollowfibers, and exposed to an agent, for example citrate, capable ofinhibiting release of a pro-inflammatory substance from a leukocyteand/or deactivating a leukocyte. The agent can be infused into a lineupstream of the fluid inlet 114 or may be infused into the SCD itselfvia a port. Alternatively, or in addition, the SCD cartridge can beprepared with the agent prior to its use. Flow rates in the ECS arechosen in the ranges described herein such that there is a low shearforce (in the ranges described herein) at the surface of the fiber toallow leukocytes to associate therewith. In this way, inhibition and/ordeactivation of the leukocytes and/or platelets is achieved orinitiated. Then, the blood in the ECS exits the SCD via fluid outlet118, which enters into an outflow line.

FIG. 2A shows an exemplary SCD cartridge 100 of FIG. 1A in an exemplaryfluid circuit. Body fluid, for example, blood, from a subject enters ablood line and is moved through that line via a pump 204. On the sameblood line, a leukocyte inhibiting agent (e.g., citrate) can be infusedat a port 206, optionally with a pump. The blood in the blood line thenenters the inlet 114 and exits the SCD cartridge 100 at outlet 118.Blood lines at the inlet 114 and outlet 118, respectively, are attachedusing blood line connectors with locking mechanisms 256. Leukocytes areshown sequestered in the ECS 112 at the external surface of the solidsupport 120, which is depicted as a single hollow fiber. A blood outflowline from the outlet 118 returns blood to the subject. Another agent,such as calcium (e.g., calcium chloride or calcium gluconate), can beinfused at a port 258 on this blood outflow line to prepare the bloodfor re-entry into the subject. In certain embodiments, the ICS cancontain xenographic or allographic cells, for example, renal tubulecells, cultured in a monolayer on the lining of the ICS 122 of eachfiber to further aid in treatment of the blood. However, in otherembodiments, the ICS is cell-free. In one embodiment of the circuit ofFIG. 2A, the lumen 122 of SCD cartridge 100 can be filled with saline.

The circuit of FIG. 2B includes the same components as FIG. 2A andoperates in the same manner, except that FIG. 2B utilizes a SCDcartridge 100 in which ultrafiltrate is produced. The SCD cartridge 100contains a plurality of porous membranes, which are hollow fibers. Theluminal space within the fibers is the ICS 122 and the surrounding spaceoutside the solid support 120 (depicted as hollow fibers) and within theSCD cartridge housing 110 is the ECS 112. Body fluid, for example, bloodcontaining leukocytes enters the inlet 114 and moves into the ECS 112surrounding the hollow fibers and exits at the outlet 118. Leukocytesequestration and inhibition and/or deactivation can be achieved asdescribed above. However, in this SCD, only the ICS inlet is capped withend cap 130. The ICS outlet 128 is not capped. Accordingly, depending onthe characteristics of the porous hollow fibers (e.g., permeability andpore size), a portion of the blood in the ECS 112 can pass across thehollow fibers, and into the ICS 112 as ultrafiltrate (UF). A tube can beconnected to the ICS outlet 128 for collecting ultrafiltrate (UF), whichmay be discarded as waste.

Flow rates and membrane characteristics for the embodiments shown in thecircuits of FIGS. 2A-2B with the SCD of FIG. 1A can be as describedbelow. For example, the ECS flow rate may be from about 100 mL/minute toabout 500 mL/minute. The flow rate of the ultrafiltrate waste (e.g., forthe SCD cartridge shown in FIG. 2B) may include, for example, flow ratesfrom about 5 mL/minute to about 50 mL/minute. In the case of the circuitin FIG. 2B, replacement fluid equal in volume to the ultrafiltratewaster produced can optionally be added to the subject.

2.B. Selective Cytopheresis Inhibitory Device as Part of a Hemodialysisor Hemofiltration System

As mentioned, in some embodiments the SCD cartridge can be part of asystem with other devices for treating blood. For example, the SCDcartridge can be a part of a hemofiltration system, a hemodialysissystem and/or a hemodiafiltration system that includes one or morefiltration cartridges separate from the SCD cartridge within the system.When describing the part of the system that is not the SCD, the term“hemofiltration” can refer to hemodialysis, hemodiafiltration,hemofiltration, and/or hemoconcentration, and “hemofilter” can include adevice (e.g., a cartridge) for performing one or more of hemodialysis,hemodiafiltration, hemofiltration, and/or hemoconcentration. Thehemofiltration cartridge(s) can be configured to be in parallel orseries with a SCD within an extracorporeal blood circuit, and associatedblood pumps and tubing can be used to move the blood through theextracorporeal circuit.

For example, as shown in FIGS. 2C and 2D, blood flows from a subjectthrough a blood line. The blood is moved through the blood line via apump 204. A leukocyte inhibiting agent (e.g., citrate) can be infusedinto the same blood line at a port 206, optionally with a pump beforeentering a conventional hemofilter 260. The blood then flows throughhollow fibers 262 in hemofilter 260. Dialysate is infused into the ECSsurrounding the hollow fibers 262 and within the housing of hemofilter260, and dialysis occurs with solutes being removed as “waste” from theblood across the hemofilter filtration membrane 262 (the hollow fibers)and into the dialysate. The dialysate flows in a counter current fashionrelative to the blood, and the dialysate is moved with a dialysate pump264. Additionally, molecules and fluid from the blood can pass acrossthe hemofilter filtration membrane 262 (the hollow fibers) asultrafiltrate, depending on the pore size through the membrane.

The exemplary system of FIG. 2C shows a circuit with the SCD cartridge100 of FIG. 1A, in which the ICS inlet and outlet ports have been cappedwith end caps. Blood exits the hemofilter 260 and enters the SCDcartridge 100 at the inlet 114. The blood then is processed through theSCD cartridge, which sequesters leukocytes on the solid support 120(depicted as hollow fibers) and inhibits release of a pro-inflammatorysubstance from a leukocyte and/or deactivates a leukocyte in the mannerdescribed for FIGS. 2A-2B, above. The blood lines into and out of theSCD cartridge 100 are attached using a connection with a lockingmechanism 256. The blood is then returned to the subject via a bloodoutflow line from the outlet 118. Another agent, such as calcium, can beinfused at a port 258 on this blood outflow line in order to prepare theblood for re-entry into the subject. In certain embodiments, theintracapillary space (ICS) of the SCD can contain xenographic orallographic cells, for example, renal tubule cells, cultured in amonolayer on the lining of the lumen of each fiber to further aid intreatment of the blood. However, in other embodiments the ICS is cellfree. In certain embodiments of the fluid circuit shown FIG. 2C, the ICS122 of the SCD 100 is filled with saline and the end ports of the ICSare capped with end caps 130 and 132.

The circuit of FIG. 2D includes the same components as FIG. 2C andoperates in the same manner, except that FIG. 2D utilizes a SCDcartridge 100 that produces ultrafiltrate (i.e., the ICS outlet port isnot capped with end caps). The flow of body fluid (e.g., blood) throughthe SCD cartridge 100 is described above in the context of FIG. 2B.Additionally, SCD cartridge 100 functions as described above, in thecontext of FIG. 2B. As noted above, SCD cartridge 100 has only the ICSinlet 126 capped with end cap 130. The ICS outlet 128 is not capped withan end cap. Accordingly, depending on the characteristics of the poroushollow fibers, a portion of the blood in the ECS 112 can pass across thehollow fibers, and into the ICS as ultrafiltrate (UF). A tube can beconnected to the ICS outlet 128 for collecting ultrafiltrate (UF), whichmay be discarded as waste.

Without wishing to be bound by theory, it is contemplated that the flowgeometry in these embodiments of the SCD system (and those shown inFIGS. 2A-2D and 3A and 3B) allows leukocytes to exist in a low shearforce environment in the ECS of the SCD cartridge and, therefore,associate with one or more internal surfaces in the SCD cartridge, forexample, the hollow fibers. Conversely, in a typical use of ahemofiltration cartridge (for example, the first device 260 in thecircuits of FIGS. 2C and 2D), blood flow through the small diameterlumens of the hollow fibers yields a higher shear force (than that inthe SCD) that prevents association of leukocytes with the hollow fibersand sequestration of leukocytes within the device. Accordingly, ahemofiltration device having the conventional flow circuit supportingits operation reversed (i.e., blood flowing outside the hollow fibersrather than inside the hollow fibers) can act as a SCD to sequesterpotentially damaging and circulating activated leukocytes. Thesesequestered leukocytes can be treated with a leukocyte inhibiting agent(e.g. citrate).

Further, it is contemplated that the inflammatory response ofsequestered leukocytes is inhibited and/or deactivated in the presenceof low Ca, (caused, for example, by citrate) before, during, and/orafter sequestration. The low-Ca, environment may inhibit theinflammatory activity of, or deactivate, the leukocytes.

In certain embodiments, the circuit of FIG. 2D can be modified such thatthe dialysate produced by hemofilter 260 can be introduced into the ICSof SCD cartridge 100 via ICS inlet 126. Although the ICS can be cellfree, it is understood that this system optionally also can includecells within the ICS 122, for example, renal tubule cells. The rate ofthe blood flow is chosen to have a sufficiently low shear force (in theranges described herein) at the surface of the porous, hollow fibers toallow sequestration of leukocytes by association with the fibers, forexample at a blood flow rate from about 100 mL/minute to about 500mL/minute. Alternatively, the blood flow rate through the extracorporealcircuit, through the lumens of the hollow fibers in the hemofilter 260,and through the ECS 112 of the SCD cartridge 100 can be about 120mL/minute. The ultrafiltrate can be moved at rates in the rangesdescribed herein, for example, at flow rates less than about 50mL/minute, from about 5 mL/minute to about 50 mL/minute, and from about10 mL/minute to about 20 mL/minute. Alternatively, the ultrafiltrateflow rate can be maintained at 15 mL/minute. Optionally, a balancedelectrolyte replacement solution (e.g., a solution containingbicarbonate base) can be infused into the bloodline on a 1:1 volumereplacement for ultrafiltrate produced. The fluid (e.g., ultrafiltrate)and blood (or leukocyte-containing fluid) can flow in the same directionor in opposite directions.

In this and other embodiments, the blood flow configuration through theSCD cartridge is opposite the blood flow configuration through a typicalhemofiltration cartridge. That is, blood flows through the interior ofthe hollow fibers of the hemofiltration cartridge in its intended useversus around the outside of the hollow fibers of the SCD cartridge.This unconventional blood flow configuration through the SCD cartridgeallows for a lower shear force within the ECS at the exterior surface ofthe hollow fiber relative to the higher shear force within the lumen ofthe hollow fibers of a hemofilter, thus facilitating sequestration ofleukocytes in the ECS of the SCD. Conversely, the blood flow through theinterior of the hollow fibers of the hemofilter prohibits leukocytesequestration due to high shear force created by blood flowing throughthe small diameter lumens of the hollow fibers. For example, the passageof blood within the interior of a hollow fiber of a hemofilter cancreate a shear force of 1.5×10⁷ dynes/cm² whereas blood flow through theECS of certain embodiments of a SCD creates a shear force of 10dynes/cm², or about 10⁶ less shear force. For comparison, the shearforce at a typical arterial wall is 6 to 40 dynes/cm² and the shearforce at a typical vein wall is 1-5 dynes/cm². Thus, a capillary wallhas a shear stress of less than 5 dynes/cm².

Accordingly, use of the SCD cartridge uses a sufficiently low shearforce at a surface in a region of a passageway configured to sequesterleukocytes to be able to associate leukocytes with that surface andsequester leukocytes, such as activated leukocytes in the region. Forexample, in some embodiments a shear force of less than 1000 dynes/cm²,or less than 500 dynes/cm², or less than 100 dynes/cm², or less than 80dynes/cm², or less than 60 dynes/cm², or less than 40 dynes/cm², or lessthan 20 dynes/cm², or less than 10 dynes/cm², or less than 5 dynes/cm²,is useful at a surface in the passageway region configured to sequesterleukocytes. It should be understood that these shear forces may beuseful in any of the SCD embodiments described herein. In certainembodiments, having two devices, such as a hemofilter and a SCD, thedifference in shear force between blood flowing in the hemofilter andblood flowing in the SCD can be at least 1000 dynes/cm².

In these and other embodiments, so long as the unconventional flowconfiguration is followed (i.e., blood flows outside of the hollowfibers, rather than inside the hollow fibers) to yield the requisiteshear force, the SCD can be comprised of a conventional (e.g., ModelF-80A, Fresenius Medical Care North America, Waltham, Mass., U.S.A.),which is approved by the FDA for use in acute and chronic hemodialysis.Similarly, the extracorporeal perfusion circuit of this or any otherembodiment can use standard dialysis arteriovenous blood tubing. Thecartridges and blood tubing can be placed in any dialysate delivery pumpsystem (e.g., Fresenius 2008H) that is currently in use for chronicdialysis.

In one exemplary system, the system includes tubing leading from asubject (a blood line) with a bag of a citrate solution infused into thetubing by an infuser. A first F-40 hemofilter cartridge (FreseniusMedical Care North America, Waltham, Mass., U.S.A.) is connected withthe blood line at a point after the citrate enters the blood line. Bloodin the blood line then flows through the interior of hollow fibers (theICS) inside the cartridge, from an end port inlet to an end port outlet,and dialysate flows outside these hollow fibers and within the cartridge(the ECS) from one side port to a second side port in a countercurrentmanner with respect to the blood flow. A dialysate/ultrafiltrate mixtureexiting from the second side port is collected. Substantially no bloodcells, platelets, or plasma cross from the ICS to the ECS, andsubstantially no leukocytes adhere to the interior of the hollow fibers.The hollow fibers are disposed parallel to one another in a bundle, andeach fiber has a diameter of approximately 240 micrometers. Furthermore,the pores of the hollow fibers are small enough to prevent passage ofalbumin, a molecule of about 30 angstroms, through the fibers, and thepores are generally this size across the entire fiber. The filteredblood then continues from the end port outlet, through tubing, to a sideport inlet of an F-80A-based cartridge (Fresenius Medical Care NorthAmerica, Waltham, Mass., U.S.A.), which operates as a SCD cartridge. Theblood flows through the ECS of the F-80A-based cartridge and exits thecartridge at a side port outlet. Any ultrafiltrate that is produced inthe F-80A-based cartridge enters the ICS and exits through an end port.The other end port of the cartridge is capped. Substantially no bloodcells, platelets, or plasma cross from the ECS to the ICS, andleukocytes adhere to the exterior of the hollow fibers for some periodof time. Blood exiting the F-80A cartridge enters tubing where a calciumsolution is infused into the blood using an infuser. Finally, the tubingreturns the processed blood to the subject. In certain embodiments, theblood flow rate in the system does not exceed 500 mL/minute, and blooddoes not displace air in the system at any point. Additionally, thepumping and infusion rates can be manually changed in view of bedsidereadings of electrolytes and white blood cell counts. An i-STAT®handheld monitoring device produces these readings from a small amountof blood withdrawn from the subject.

It is contemplated that the risk of using such a system is similar tothe risk associated with hemodialysis treatment and includes, forexample, clotting of the perfusion circuit, air entry into the circuit,catheter or blood tubing kinking or disconnection, and temperaturedysregulation. However, dialysis machines and associated dialysis bloodperfusion sets have been designed to identify these problems duringtreatment with alarm systems and to mitigate any clot or air embolism tothe subject with clot filters and air bubble traps. These pump systemsand blood tubing sets are FDA approved for this treatment indication.

As mentioned above, infusion of a leukocyte inhibition agent, forexample, citrate, can be local to the SCD, regional, or throughout thesystem. In this or any embodiment, citrate can also be used as ananti-clotting agent, in which case perfusion throughout the system wouldbe useful. Clinical experiences suggest that if clotting occurs within ahemofiltration system, it is initiated in the first dialysis cartridge.Anticoagulation protocols, such as systemic heparin or regional citrate,are currently established and routinely used in clinical hemodialysis.

2.C. Selective Cytopheresis Inhibitory Device as Part of aCardiopulmonary Bypass System

As shown in FIGS. 3A-3B, a SCD cartridge can be used within acardiopulmonary bypass (CPB) circuit to treat and/or preventinflammatory conditions secondary to surgeries (e.g., bypass surgery).FIGS. 3A and 3B show the SCD cartridge of FIG. 1A in exemplary CPBsystems. CPB is used to divert blood from both the left and right sidesof the heart and lungs. This is achieved by draining blood from theright side of the heart and perfusing the arterial circulation. However,since systemic-to-pulmonary collaterals, systemic-to-systemiccollaterals, and surgical site bleeding return blood to the left side ofthe heart, special drainage mechanisms of the left side of the heart arerequired during CPB. Optionally, cardioplegia can be delivered through aspecial pump and tubing mechanism. A standard CPB system has severalfeatures that can be broadly classified into three subsystems. The firstsubsystem is an oxygenating-ventilating subsystem that supplies oxygenand removes carbon dioxide from the blood. The second subsystem is atemperature control system. The third subsystem includes in-linemonitors and safety devices.

As shown in the embodiment of FIG. 3A, blood is moved via a venouscannula 300 from a subject into a blood line 310. Blood flows throughthe blood line 310, passing a recirculation junction 320, which isconnected to a SCD outflow line 330. The SCD outflow line 330 containsblood treated by the SCD device 100. The blood in the blood line 310mixes with the SCD-treated blood and continues to a venous reservoir 350and onto an oxygenator 360 where the blood is oxygenated. The oxygenatedblood then flows from the oxygenator 360 to a junction 370 with a SCDinflow line 380. Here, where a portion of the blood in the blood line310 is diverted to the SCD 100 via the SCD inflow line 380 for treatmentby the SCD cartridge 100. The flow of blood through the SCD inflow line380 is controlled by a pump 382. The SCD cartridge 100 is designed tosequester select cells associated with inflammation, for example,leukocytes or platelets. Blood containing leukocytes enters the inlet114 and moves into the ECS 112 (see in FIG. 1A) surrounding the hollowfibers. Leukocytes are sequestered in the device, for example, on thefluid contacting surface of solid support 120 (see in FIG. 1A) (i.e.,the exterior surface of the hollow fibers). Flow rates at pump 382 canbe chosen at ranges described herein such that there is a low shearforce (in the ranges described herein) at the surface of the hollowfibers to allow leukocytes to associate therewith. Blood in the ECS 112(see in FIG. 1A) exits the SCD via outlet 118 and enters the SCD outflowline 330. At junction 370, a portion of the blood in the blood line 310also continues to an arterial filter/bubble trap 390, before beingreturned to the subject at an arterial cannula 395.

Although no agents need be added to the blood, in one embodiment, acitrate feed 335 and citrate pump 336 add citrate to the blood in theSCD inflow line 380 and a calcium feed 345 and calcium pump 346 addcalcium to the blood in the SCD outflow line 330. Citrate (or anotherleukocyte inhibiting agent described herein) is added to the bloodflowing into the SCD cartridge 100 from the citrate feed 335 to inhibitand/or deactivate cells associated with inflammation, such asleukocytes. Calcium can be added back into the blood to prepare theblood for reentry into the subject.

The circuit shown in FIG. 3B is different from the circuit of FIG. 3A inthat it does not recirculate blood within the circuit, for example, at arecirculation junction 320 (see, FIG. 3A). Rather, as shown in FIG. 3B,blood is moved via the venous cannula 300 from a subject into the bloodline 310, where the blood flows directly to the venous reservoir 350 andonto an oxygenator 360 where the blood is oxygenated. The oxygenatedblood then flows from the oxygenator 360 to the junction 370 with theSCD inflow line 380. Here, a portion of the blood in the blood line 310is diverted to the SCD cartridge 100 via the SCD inflow line 380 forsequestration of leukocytes by the SCD cartridge 100, as described abovefor FIG. 3A. Blood exiting the SCD cartridge 100 enters the SCD outflowline 330 and mixes with oxygenated blood at junction 386. After bloodfrom the SCD cartridge mixes with blood in the blood line 310 itcontinues in the blood line 310 to the arterial filter/bubble trap 390,before being returned to the subject at the arterial cannula 395.

A citrate feed 335 and citrate pump 336 to add citrate to the blood inthe SCD inflow line 380 and a calcium feed 345 and calcium pump 346 toadd calcium to the blood in the SCD outflow line 330. As described forFIG. 3A, citrate or any other leukocyte inhibiting agent is added to theblood from the citrate feed 335 to inhibit and/or deactivate cellsassociated with inflammation, such as leukocytes. Calcium can be addedback into the blood to prepare the blood for reentry into the subject.

2.D. Additional Features of Selective Cytopheresis Inhibitory Devices

In some embodiments, the SCD cartridges are configured for treatingand/or preventing a certain disorder. It is understood, however, that anumber of different configurations can be used to treat and/or prevent aparticular disorder.

Moreover, the SCD cartridge can be oriented horizontally or verticallyand placed in a temperature controlled environment. The temperature of aSCD cartridge containing cells preferably is maintained at about 37° C.to about 38° C. throughout the SCD's operation to ensure optimalfunction of the cells in the SCD cartridge. For example, but withoutlimitation, a warming blanket may be used to keep the SCD cartridge atthe appropriate temperature. If other devices are utilized in thesystem, different temperatures may be needed for optimal performance.

In some embodiments, the SCD cartridges and/or the fluid circuitsincorporating the SCD cartridges are controlled by a processor (e.g.,computer software). In such embodiments, a device can be configured todetect changes in activated leukocyte levels within a subject andprovide such information to the processor (e.g., information relating toleukocyte levels and/or increased risk for developing an inflammationdisorder). In some embodiments, when a certain activated leukocyte levelis reached or a subject is deemed at a certain risk for developing aninflammation disorder (e.g., SIRS), the subject's blood is processedthrough a SCD for purposes of reducing the possibility of developing aninflammation disorder. In some embodiments, the fluid circuit canautomatically process the subject's blood through the SCD in response tothese measurements. In other embodiments, a health professional isalerted to the elevated leukocyte level or increased risk within thesubject, and the professional initiates the treatment.

It is contemplated that the cartridges of the present invention can beincluded with various kits or systems. For example, the kits or systemsmay include the SCD cartridges of the present invention, leukocyteinhibiting agents (e.g., calcium chelating agents, such as citrate),allographic cells (e.g., renal tubule cells), or other parts.Additionally, the SCD cartridges may be combined with various surgicalinstruments necessary for implanting the filtration device into asubject.

3. Inhibition and/or Deactivation of Cells Associated with Inflammation

The SCD cartridges are configured, and the methods of the presentinvention when performed inhibit release of a pro-inflammatory substancefrom leukocytes and/or deactivate leukocytes, such as activatedleukocytes, in a subject's blood such that an inflammatory responsewithin the subject is prevented and/or diminished. Various techniquescan be used. For example, in some embodiments, the SCD cartridges andthe fluid circuits incorporating one or more of the SCD cartridges caninhibit release of a pro-inflammatory substance from a leukocyte and/ordeactivate a leukocyte by exposing the leukocytes (e.g., sequesteredactivated and/or primed leukocytes) to leukocyte inhibiting agents. Aleukocyte inhibiting agent can be bound, covalently or non-covalently,to a fluid contacting surface of the SCD cartridge, for example, ahollow fiber. Additionally or alternatively, a leukocyte inhibitingagent can be infused into the SCD cartridge or a circuit incorporating aSCD cartridge before, during, or after sequestration of the leukocytes,for example, at or near a membrane surface.

The present invention is not limited to a particular type or kind ofleukocyte inhibiting agent. Leukocyte inhibiting agents include, forexample, anti-inflammatory biological agents, anti-inflammatory smallmolecules, anti-inflammatory drugs, anti-inflammatory cells, andanti-inflammatory membranes. In some embodiments, the leukocyteinhibiting agent is any material or compound capable of inhibitingactivated leukocyte activity including, but not limited to,non-steroidal anti-inflammatory drugs (NSAIDs), anti-cytokines, imatinibmesylate, sorafenib, sunitinib malate, anti-chemokines,immunosuppressant agents, serine leukocyte inhibitors, nitric oxide,polymorphonuclear leukocyte inhibitor factor, secretory leukocyteinhibitor, and calcium chelating agents. Examples of calcium chelatingagents include, but are not limited to, citrate, sodiumhexametaphosphate, ethylene diamine tetra-acetic acid (EDTA),triethylene tetramine, diethylene triamine, o-phenanthroline, oxalicacid and the like. The leukocyte inhibiting agent can be any protein orpeptide known to inhibit leukocytes or immune cells including, but notlimited to, angiogenin, MARCKS, MANS, Complement Factor D, the disulfideC39-C92 containing tryptic angiogenin fragment LHGGSPWPPC⁹²QYRGLTSPC³⁹K(SEQ ID NO: 1) and synthetic homologs of the same; the agent also can bethose proteins, peptides, and homologs reported by Tschesche et al.(1994) J. BIOL. CHEM. 269(48): 30274-80, Horl et al. (1990) PNAS USA 87:6353-57, Takashi et al. (2006) AM. J. RESPIRAT. CELL AND MOLEC. BIOL.34: 647-652, and Balke et al. (1995) FEBS LETTERS 371: 300-302, that mayfacilitate inhibition of release of a pro-inflammatory substance from aleukocyte and/or deactivate a leukocyte. Moreover, the leukocyteinhibiting agent can be any nucleic acid known to inhibit release of apro-inflammatory substance from the leukocyte and/or deactivate theleukocyte. The leukocyte inhibiting agent can be in solution orlyophilized

Any amount or concentration of leukocyte inhibiting agent can be used toinhibit the release of pro-inflammatory substances from a leukocyteand/or deactivate the leukocyte. The leukocyte inhibiting agent can beintroduced into a passageway, passageway region, device, device region,or system region of a system by any methods known in the art. Forexample, the leukocyte inhibiting agent can be infused at a port. Theamount of leukocyte inhibiting agent infused in a passageway can besufficient to inhibit release of a pro-inflammatory substance from aleukocyte and/or deactivate a leukocyte sequestered within the samepassageway or within an adjacent passageway. In some embodiments, aleukocyte inhibiting agent, for example, citrate, can be infused intothe system, a region of the system, or one or more devices within thesystem, including devices that perform other functions and do notsequester leukocytes. More particularly, the leukocyte inhibiting agent(e.g. citrate) can be infused upstream from, into, or downstream from apassageway that sequesters leukocytes. Alternatively, the leukocyteinhibiting agent can be contained in one or more passageways, passagewayregions, devices, or system regions within a system. For example, aleukocyte inhibiting agent can be bound to a surface in the passagewayconfigured to sequester leukocytes, or in another passageway, in anamount sufficient to inhibit release of a pro-inflammatory substancefrom the leukocytes and/or deactivate the leukocytes.

The inhibition of release of a pro-inflammatory substance from aleukocyte and/or deactivation of a leukocyte can occur temporallybefore, during, and/or after sequestration of the leukocyte. Moreover,the leukocyte can remain inhibited or deactivated for a period of timefollowing sequestration. In certain embodiments, a leukocyte can beinhibited or deactivated during the period of time that the leukocyte isexposed to a target concentration of a leukocyte inhibiting agent or isexposed to a target a concentration of Ca, (typically from about 0.20mmol/L to about 0.40 mmol/L) that results from exposure to a leukocyteinhibiting agent such as citrate. The period of time that the leukocyteis exposed to the target concentration of leukocyte inhibiting agent ortarget concentration of Ca, can precede, include, and/or follow theperiod of time that the leukocyte is sequestered. In certainembodiments, the leukocyte can continue to become or remain inhibited ordeactivated for a period of time following exposure to the leukocyteinhibiting agent.

The time of exposure to the leukocyte inhibiting agent can varydepending upon the agent used, the extent of leukocyte activation, theextent of production of pro-inflammatory substances, and/or the degreeto which the inflammatory condition has compromised patient health.Exposure can be, for example, from 1 to 59 seconds, from 1 to 59minutes, from 1 to 24 hours, from 1 to 7 days, one or more weeks, one ormore months, or one year or more. The leukocyte inhibiting agent can beapplied to the system before or during operation the system. In certainembodiments, the leukocyte inhibiting agent is applied during operationof the system and the amount of leukocyte inhibiting agent applied tothe system is monitored.

In some embodiments, a leukocyte inhibiting agent can be titrated intothe system (e.g., at a port 206 as shown in FIGS. 2A-2D or from a feed335 and pump 336 as shown in FIGS. 3A and 3B). The titration can beadjusted relative to a monitored blood characteristic. For example,citrate can be titrated into the system to keep the Ca, in the blood ata certain level, for example, at a Ca, concentration of about 0.2 toabout 0.4 mmol/L. Any type of citrate that is biologically compatiblecan be used, for example, 0.67% trisodium citrate or 0.5% trisodiumcitrate. See, e.g., Tolwani et al. (2006) CLIN. J. AM. Soc. NEPHROL. 1:79-87. In some embodiments, a second solution can be added into thesystem following inhibition of the release of pro-inflammatorysubstances from a leukocyte and/or deactivation of the leukocyte (e.g.,at port 258 as shown in FIGS. 2A-2D, or from a feed 335 and pump 336 asshown in FIGS. 3A and 3B), to readjust the blood for reentry into thesubject. For example, in embodiments in which a calcium chelating agentis used as the leukocyte inhibiting agent, calcium can be added backinto the blood before reentry into the subject.

In one embodiment, a 1000 mL bag containing a citrate solution, forexample ACD-A (Baxter Fenwal, Chicago Ill.; contents per 100 mL:dextrose 2.45 g, sodium citrate 2.2 g, citric acid 730 mg, pH 4.5-5.5 at25° C.) can be attached to an infusion pump and then attached to anarterial line (outflow from subject to devices) of the system (e.g. atport 206; the outflow from a subject in a CPB situation is called avenous line, and infusion occurs from, for example, the feed 335 andpump 336). A negative pressure valve can be employed to facilitatecitrate pump function (infusing into a negative pressure area proximalto the blood pump). The initial rate of citrate infusion can beconstant, for example, about 1.5 times, in mL/hour, the blood flow rate,in mL/minute (e.g., if the blood flow rate is about 200 mL/minute, thenthe initial constant rate of citrate infusion may be about 300 mL/hour).In addition, a calcium chloride infusion at a concentration of about 20mg/mL may be added near the venous port of the system (e.g., port 258 ofFIGS. 2A-2D); the analogous location in the CPB situation is shown as afeed 335 and pump 336 in FIGS. 3A and 3B). The initial calcium infusioncan be set at 10% of the citrate infusion rate (e.g., 30 mL/hour). TheCa, can be monitored continuously or at various times, for example,every two hours for the first eight hours, then every four hours for thenext sixteen hours, then every six to eight hours thereafter. Themonitoring can be increased as needed and can be monitored at more thanone location in the system, for example, after citrate infusion andafter calcium infusion.

Exemplary citrate and calcium chloride titration protocols are shown inTable 3 and in Table 4, respectively. In this embodiment, the target Ca,range in the SCD is from about 0.20 mmol/L to about 0.40 mmol/L, withthe Ca, target concentration achieved by infusion of citrate (e.g.,ACD-A citrate solution). As this is a dynamic process, the rate ofcitrate infusion may need to be changed to achieve the target Ca, rangein the SCD. The protocol for doing so is shown below, with infusionoccurring at the infusion points described above.

TABLE 3 Citrate Infusion Titration Guidelines Circuit Ionized Ca²⁺Infusion Adjustment with ACD-A (between the SCD and patient) citratesolution (as described above) If circuit ionized Ca²⁺ is less thendecrease the rate of citrate than 0.20 mmol/L infusion by 5 mL/hour Ifcircuit ionized Ca²⁺ is then make no change to the rate 0.20-0.40 mmol/Lof citrate infusion (Optimal Range) If circuit ionized Ca²⁺ is thenincrease the rate of citrate 0.41-0.50 mmol/L infusion by 5 mL/hour Ifcircuit ionized Ca²⁺ is then increase the rate of citrate greater than0.50 mmol/L infusion by 10 mL/hour

TABLE 4 Calcium Infusion Titration Guidelines Patient Ionized Ca²⁺ Ca²⁺Infusion (20 mg/mL CaCl₂) (drawn systemically from patient) AdjustmentIf patient ionized Ca²⁺ is greater than then decrease the rate of CaCl₂1.45 mmol/L infusion by 10 mL/hour If patient ionized Ca²⁺ is 1.45mmol/L then decrease the rate of CaCl₂ (maximum allowable amount)infusion by 5 mL/hour If patient ionized Ca²⁺ is 0.9 mmol/L thenincrease the rate of CaCl₂ (minimum allowable amount) infusion by 5mL/hour If patient ionized Ca²⁺ is less than then administer a 10 mg/kg0.9 mmol/L CaCl₂ bolus and increase the rate of CaCl₂ infusion by 10mL/hour Default Range (preferred target level) 1.0-1.2 mmol/L

It should be understood that the deactivation techniques describedherein also can apply to platelets. In certain embodiments, agents usedto deactivate a platelet and/or inhibit release of a pro-inflammatorysubstance from a platelet include, but are not limited to, agents thatinhibit thrombin, antithrombin III, meglatran, herudin, Protein C andTissue Factor Pathway Inhibitor. In addition, some leukocyte inhibitingagents can act as platelet inhibiting agents. For example, calciumchelating agents, such as citrate, sodium hexametaphosphate, ethylenediamine tetra-acetic acid (EDTA), triethylene tetramine, diethylenetriamine, o-phenanthroline, and oxalic acid can deactivate a plateletand/or inhibit release of a pro-inflammatory substance from a platelet.

4. Indications

The SCD cartridges, circuits incorporating the SCD cartridges, andmethods of the present invention can be used for treating and/orpreventing a number of conditions that are associated with inflammation.As used herein, the term “inflammatory condition,” includes anyinflammatory disease, any inflammatory disorder, and/or any leukocyteactivated disorder wherein the organism's immune cells are activated.Such a condition can be characterized by (i) a persistent inflammatoryresponse with pathologic sequelae and/or (ii) infiltration ofleukocytes, for example, mononuclear cells and neutrophils, leading totissue destruction. Inflammatory conditions include primary inflammatorydiseases arising within a subject and/or secondary inflammatorydisorders arising as a response to a medical procedure. The systems,devices, and methods of the present invention can treat any inflammatorycondition for any subject. As used herein, the term “subject” refers toany animal (e.g., a mammal), including, but not limited to, a human(e.g., a patient), non-human mammals, for example, a non-human primatesand other experimental animals, farm animals, companion animals, and thelike, which is to be the recipient of a particular diagnostic test ortreatment.

Leukocytes, for example, neutrophils, are major contributors to thepathogenesis and progression of many clinical inflammatory conditions,including systemic inflammatory response syndrome (SIRS), sepsis,ischemia/reperfusion injury and acute respiratory distress syndrome(ARDS). Several different and diverse types of leukocytes exist;however, they are all produced and derived from a pluripotent cell inthe bone marrow known as a hematopoietic stem cell.

Leukocytes, also referred to as white blood cells, are found throughoutthe body, including in the blood and lymphatic system. There are severaldifferent types of leukocytes including granulocytes and agranulocytes.Granulocytes are leukocytes characterized by the presence of differentlystaining granules in their cytoplasm when viewed under light microscopy.These granules contain membrane-bound enzymes, which primarily act inthe digestion of endocytosed particles. There are three types ofgranulocytes: neutrophils, basophils, and eosinophils, which are namedaccording to their staining properties. Agranulocytes are leukocytescharacterized by the absence of granules in their cytoplasm and includelymphocytes, monocytes, and macrophages.

Platelets, or thrombocytes, also contribute to inflammatory conditions,as well as to homeostasis. Upon activation, platelets aggregate to formplatelet plugs, and they secrete cytokines and chemokines to attract andactivate leukocytes. Platelets are found throughout the body'scirculation and are derived from megakaryocytes.

The molecules that are primarily responsible for initiation of leukocyteand platelet adhesion to endothelium are P-selectin and von Willebrandfactor, respectively. These molecules are found in the same granules,known as Weibel-Palade bodies, in endothelial cells. Upon activation ofendothelial cells, the Weibel-Palade bodies migrate to the cell membraneto expose P-selectin and soluble von Willebrand factor at theendothelial cell surface. This, in turn, induces a cascade of leukocyteand platelet activity and aggregation.

Accordingly, the systems, devices, and methods of the present inventioncan treat and/or prevent any inflammatory condition, including primaryinflammatory diseases arising within a subject and/or secondaryinflammatory disorders arising as a response to a medical procedure(e.g., dialysis or cardio-pulmonary bypass). Examples of applicableinflammatory conditions, including inflammatory diseases and/ordisorders, include, but are not limited to, systemic inflammatoryresponse syndrome (SIRS), polyarteritis, Wegener's granulomatosis,autoimmune vasculitis, anti-neutrophil cytoplasmic antibody (ANCA)vasculitis, extracorporeal membrane oxygenation (ECMO), cardiopulmonarybypass syndrome, acute respiratory distress syndrome (ARDS), acute lunginjury (ALI), chronic obstructive pulmonary disease (COPD), sepsis,rheumatoid arthritis, systemic lupus erythematosus, inflammatory boweldisease, multiple sclerosis (MS), psoriasis, allograft rejection,asthma, acute renal failure, chronic renal failure (CRF), end stagerenal disease (ESRD), cardiorenal syndrome (CRS), chronic heart failure(CHF), stroke, myocardial infarction (MI), hepatorenal syndrome,cirrhosis of the liver, diabetes mellitus (type 2 diabetes), and acuteorgan failure from ischemic reperfusion injury to myocardium, centralnervous system, liver, kidney, or pancreas.

Additional examples of inflammatory conditions include, but are notlimited to, transplant (such as organ transplant, acute transplant,xenotransplant) or heterograft or homograft (such as is employed in burntreatment) rejection; ischemic or reperfusion injury such as ischemic orreperfusion injury incurred during harvest or organ transplantation,myocardial infarction or stroke; transplantation tolerance induction;arthritis (such as rheumatoid arthritis, psoriatic arthritis orosteoarthritis); respiratory and pulmonary diseases including but notlimited to chronic obstructive pulmonary disease (COPD), emphysema, andbronchitis; ulcerative colitis and Crohn's disease; graft vs. hostdisease; T-cell mediated hypersensitivity diseases, including contacthypersensitivity, delayed-type hypersensitivity, and gluten-sensitiveenteropathy (Celiac disease); contact dermatitis (including that due topoison ivy); Hashimoto's thyroiditis; Sjogren's syndrome; AutoimmuneHyperthyroidism, such as Graves' Disease; Addison's disease (autoimmunedisease of the adrenal glands); Autoimmune polyglandular disease (alsoknown as autoimmune polyglandular syndrome); autoimmune alopecia;pernicious anemia; vitiligo; autoimmune hypopituatarism; Guillain-Barresyndrome; other autoimmune diseases; glomerulonephritis; serum sickness;uticaria; allergic diseases such as respiratory allergies (hayfever,allergic rhinitis) or skin allergies; scleroderma; mycosis fungoides;acute inflammatory and respiratory responses (such as acute respiratorydistress syndrome and ischemia/reperfusion injury); dermatomyositis;alopecia greata; chronic actinic dermatitis; eczema; Behcet's disease;Pustulosis palmoplanteris; Pyoderma gangrenum; Sezary's syndrome; atopicdermatitis; systemic sclerosis; morphea; trauma, such as trauma from agun, knife, automobile accident, fall, or combat; and cell therapy, suchas autologous, allogenic or xenogenic cell replacement. Additionalinflammatory conditions are described elsewhere herein or are otherwiseknown in the art.

The systems, devices, and methods of the present invention may also beused to support the development and use of tissues and organs ex vivo.For example, the present invention may be used to support organharvesting procedures for transplantation, tissue engineeringapplications, ex vivo generation of organs, and the manufacture of anduse of bio-microelectromechanic al systems (MEMs).

In light of the foregoing description, the specific non-limitingexamples presented below are for illustrative purposes and not intendedto limit the scope of the invention in any way.

EXAMPLES Example 1. Treatment of Inflammation Associated with AcuteSepsis in an Animal Model

Activated leukocytes, especially neutrophils, are major contributors tothe pathogenesis and progression of sepsis as well as other clinicalinflammatory disorders. This example describes in vivo experiments thatevaluate the effect of different SCD cartridges on leukocytesequestration and deactivation. The results demonstrate that the choiceof a particular SCD cartridge can have a profound effect on thepathogenesis and progression of sepsis in a large animal model. Inparticular, the results demonstrate that a SCD cartridge having a largersequestration area is more effective than a SCD cartridge having asmaller sequestration area in alleviating complications associated withsepsis and in prolonging survival.

(I) Methods and Materials A—Animal Model

The efficacy of the SCD cartridge in treating inflammation was evaluatedin a well-established porcine model of acute septic shock. (See, e.g.,Humes et al. (2003) CRIT. CARE MED. 31:2421-2428.)

Pigs weighing 30-35 kg were utilized. After administration of anesthesiaand intubation, the pigs underwent placement of an arterial catheter anda Swan-Ganz thermodilution catheter (which were connected totransducers) to monitor arterial blood pressure, cardiac output, andcentral venous pressures. An ultrasonic flow probe was placed on a renalartery for continuous assessment of renal blood flow (RBF).

To induce septic shock, the pigs received 30×10¹⁰ bacteria/kg bodyweight of E. coli into their peritoneal cavities. To better replicatethe human clinical situation, the antibiotic Cefriaxione (100 mg/kg) wasadministered 15 minutes after bacteria infusion. During the first hourfollowing bacteria infusion, all animals were resuscitated with 80 mL/kgof crystalloid and 80 mL/kg of colloid. All treatment groups receivedidentical volume resuscitation protocols. No animal received vasopressoror inotropic agents.

B—Extracorporeal Circuit Containing the SCD Cartridge

Immediately after bacterial administration, the animals were connectedto an extracorporeal circuit containing a standard continuous renalreplacement therapy (CRRT) hemofilter and a SCD device, as depicted inFIG. 4. The hemofilter was a Fresenius F-40 hemofiltration cartridge(Fresenius AG). The SCD cartridge (CytoPherx, Inc.) was connected to theblood port of the hemofilter through its side port using a special bloodline connector. Two types of SCD cartridges were tested. The first typeof SCD cartridge (based on a Fresenius F-40 hemofiltration cartridge)had a membrane surface area of 1.0 m² facing the extracapillary space,which had an ECS fill volume of 130 mL. The second type of SCD cartridge(based on a Fresenius F-80A hemofiltration cartridge) had a membranesurface area of 2.5 m² facing the extracapillary space, which had an ECSfill volume of 250 mL. The F-40 and F-80A SCD cartridges each containedpolysulfone hollow fibers with an inner diameter of 200 μm and a wallthickness of 40 μm. The pressure drop across the SCD was 70-75 mmHgEither the Gambro AK-10 or the Fresenius 2008H dialysis pump system wasutilized for these experiments. Extracorporeal blood flow was regulatedat 100-150 ml/min.

A balanced electrolyte replacement solution (Na 150 mEq/L, Cl 115 mEq/L,HCO₃ 38 mEq/L, Ca 2.5 mEq/L, and Mg 1.6 mEq/L in Dextrose 5%) wasinfused into the blood line on a 1:1 volume replacement basis for thenet ultrafiltrate which would exit the circuit. In addition, continuousvolume resuscitation with normal saline at 150 mL/h was employed tomaintain mean arterial pressure and cardiac output in the treatedanimals.

As a control, one group animals (n=3) underwent extracorporeal bloodperfusion in a circuit containing the hemofilter alone but without theSCD device. These animals also received regional citrate infusion andwere referred to as the conventional citrate (Con-citrate) group. Asecond group of animals was treated similarly to the SCD group withcitrate but without bacterial infusion. These animals were referred toas the non-septic control (NS-control) group.

C—Anticoagulation Process

The anticoagulation process was a critical variable in this series ofexperiments. One group of animals referred to as the SCD-heparin group(SCD-H, n=12), received systemic heparinization to maintain patency ofthe extracorporeal circuit with targeted activated clotting times (ACTs)of 200-300 sec and treated with a SCD cartridge based on the FreseniusF-40 cartridge with a membrane surface area of 1.0 m² facing theextracapillary space. A second group of animals referred to as theSCD-citrate, F-40 group (SCD-C, F-40; n=13) were treated with SCDcartridges based on the Fresenius F-40, cartridge with a membranesurface area of 1.0 m² facing the extracapillary space received regionalcitrate anticoagulation (Pinnick, R. V. et al., (1983) N. ENGL. J. MED.,308(5): 258-261; Lohr, J. W. et al., (1989) AM. J. KIDNEY DIS.,13(2):104-107; Tobe, S. W. et al. (2003) J. CRIT. CARE, 18(2): 121-129).In addition, a third group of animals also received regional citrateanticoagulation and were treated with SCD cartridges based on theFresenius F-80A, with a membrane surface area of 2.5 m² facing theextracapillary space (SCD-C, 2.5; n=3). Regional citrate coagulation wasachieved by infusing citrate dextrose-A (ACD-A, Baxter) pre-hemofilterat a rate of 2.5-5.0 mM citrate per 1000 mL whole blood. Thisessentially lowered iCa concentration in the circuit to 0.2-0.5 mmol/L.Calcium chloride was infused into the venous return of the circuit tomaintain systemic iCa values of 1.1-1.3 mmol/L. iCa levels weremonitored using an iSTAT reader (Abbott Labs).

D—Complete Blood Counts, Serum Chemistries, and Systemic InflammationParameters

Complete blood counts and serum chemistries were measured with a Hemavetautomated analyzer (Drew Scientific) and a VET Test automated analyzer(IDEXX), respectively. Serum myeloperoxidase (MPO) activity was measuredusing a modified o-dianisidine assay containing 4-aminobenzoic acidhydrazide as a potent and specific inhibitor of MPO (Fietz S, et al.,(2008) RES. VET. SCI., 84(3):347-353). Cytokine concentrations,including IL-1β, IL-6, IL-8, IL-10, TNF-α and IFN-γ, were measured withcommercially available enzyme-linked immunosorbent assay (ELISA) kitsfrom R&D Systems.

E—Assessment of Leukocyte Activation

FITC-conjugated anti-porcine CD11b antibody (SeroTec) was added topre-chilled peripheral blood. Red blood cells were lysed and theremaining leukocytes were fixed by addition of a FACS lysing solution(Becton-Dickinson). Cells were collected by centrifugation andresuspended for flow-cytometric analysis. CD11b expression wasquantitatively assessed as mean fluorescent intensity (MFI) with anAccuri flow cytometer.

Peripheral blood mononuclear cells (PBMCs) were isolated from the venousblood. Mononuclear cells were isolated using standard Ficoll-Hypaquegradient technique (Humes et al. (2003) CRIT. CARE MED. 31:2421-2428).These cells were then incubated for 24 hours in culture platescontaining RPMI-1640 medium supplemented with antibiotics in the absenceor the presence of 1 μg/mL of lipopolysaccharide (LPS). The supernatantswere collected and cytokine concentrations measured. The ratio ofstimulated to unstimulated cytokine concentrations in the supernatantswas then calculated.

F—Lung Histology and Immunohistochemistry

Lung samples were harvested post-mortem from septic pigs treated underSCD-citrate or SCD-heparin conditions. Two random sections from each ofthe 5 lobes of the lungs were processed for cryosections. Frozen lungsamples were cut at 5-μm thickness and fixed with 4% paraformaldehyde onice for 10 minutes. Tissues were stained with hematoxylin and eosin forlight microscopic examination, or for CD11b evaluation; nonspecificadsorption was minimized by incubating the section in goat serum in PBSfor 1 hour.

For evaluation of CD11b expression, lung sections were incubated withprimary anti-CD11b antibody at recommended dilutions for 1 hour at roomtemperature. This was followed by incubation with an anti-mouse IgGAlexafluor594 conjugate (1:200 dilution) at room temperature for 30minutes, and counterstaining the nuclei with DAPI. ImageJ software(Abramoff, M.D. (2004) Biophotonics International, 11(7): 36-42) wasused to quantify the percentage of CD11b-positive areas in random 10×images taken with fixed capture settings. Cell number normalization wasachieved by determining the percentage of DAPI-positive areas in thesame picture. The results were expressed as the ratio of percentCD11b-positive area by percent DAPI-positive area.

G—Cell Elution from SCD Cartridges

Prior to disconnecting the circuit, blood was returned to the pig byperfusion with replacement fluid. The SCD extracapillary space (ECS) wasthen continuously flushed with replacement fluid until the perfusatefluid was free of visible blood. After draining off the replacementfluid, the cartridge was either fixed for histologic processing (Humes,H. D. et al., (2010) BLOOD PURIFICATION, 29:183-190) or exchanged with astabilization buffer containing a calcium chelating agent. Adherentcells were mechanically removed from the SCD eluent for analysis. Toensure that all cells adherent to the device were eluted, severalcartridges were digested after elution with a DNA isolation buffer (SDSand proteinase K). The DNA extracted in this manner, on average, wasless than 5 percent of the eluted DNA from the cartridge.

H—Statistical Analysis

Group comparisons at multiple time points utilized ANOVA with repeatedmeasures. Otherwise, comparisons between groups used Students' T test,paired or unpaired, as appropriate. Statistical significance was definedas p<0.05.

(II) Results and Discussion A—Observations of Cardiovascular Parameters

The porcine model of septic shock was utilized to evaluate theeffectiveness of SCD cartridges having different membrane surface areascombined with either systemic heparin or regional citrateanticoagulation. Specifically, one group of animals (SCD-H) was treatedwith systemic heparin anticoagulation and either an F-40-based SCD or anF-80A-based SCD cartridge. A second group of animals was treated withregional citrate anticoagulation and an F-40-based SCD cartridge (SCD-C,F-40). A third group of animals was treated with regional citrateanticoagulation and an F-80A-based SCD cartridge (SCD-C, F-80A). Afourth group of animals received citrate without a SCD device(con-citrate).

As indicated in Table 5 and FIG. 5A, the intraperitoneal administrationof bacteria induced a rapid and profound decline in mean arterialpressure (MAP) in all four groups of animals. This decline wasprogressive and ultimately fatal.

TABLE 5 Cardiovascular Parameters Parameter 0 1 2 3 4 5 6 7 8 9 10 11Cardiac output, L/min SCD-Citrate F-40 4.3 ± 4.9 ± 4.7 ± 4.4 ± 3.7 ± 2.7± 2.3 ± 2.1 ± 1.7 ± 1.0 ± 1.1 ± 1.1 ± 0.3 0.2 0.2 0.3 0.2 0.3 0.2 0.30.1 0.3 0.1 0.1 SCD-Citrate F-80A 3.9 ± 5.2 ± 4.8 ± 4.5 ± 4.1 ± 3.7 ±3.1 ± 2.8 ± 2.4 ± 2.1 ± 1.4 ± 0.8 0.6 0.3 0.4 0.5 0.5 0.2 0.2 0.3 0.40.2 SCD-Heparin 4.1 ± 5.2 ± 4.2 ± 3.8 ± 2.6 ± 1.7 ± 1.5 ± 1.3 ± 1.1 0.30.2 0.3 0.2 0.2 0.2 0.2 0.2 Con-Citrate 4.5 ± 4.7 ± 5.2 ± 3.6 ± 3.8 ±2.6 ± 1.5 ± 1 0.3 0.5 1.2 0.5 0.5 0.4 0.3 Systolic blood pressure, mmHgSCD-Citrate F-40 96.9 ± 99.9 ± 94.5 ± 88.9 ± 80.3 ± 69.7 ± 69.5 ± 68.0 ±55.0 ± 45.8 ± 53.5 ± 36.5 ± 5.7 2.2 3.2 4.4 4.1 6.5 7.0 6.5 8.7 5.1 0.58.5 SCD-Citrate F-80A 118.7 ± 98.7 ± 65.7 ± 70.3 ± 69.0 ± 67.0 ± 59.3 ±60.7 ± 61.7 ± 51.0 ± 33.3 ± 29.2 9.7 4.4 4.1 5.1 4.6 4.5 8.7 8.1 4.5 7.9SCD-Heparin 96.6 ± 104.9 ± 94.4 ± 88.0 ± 76.4 ± 58.4 ± 52.4 ± 41.0 ± 554.7 4.8 6.5 4.4 6.3 4.4 8.4 12.1 Con-Citrate 87.3 ± 103.0 ± 77.3 ± 69.0± 74.7 ± 51.7 ± 30.0 ± 1.8 11.4 4.2 3.2 13.7 4.9 20.0 Diastolic bloodpressure, mmHg SCD-Citrate F-40 60.5 ± 64.5 ± 54.0 ± 45.5 ± 42.1 ± 39.7± 39.9 ± 36.1 ± 26.3 ± 26.5 ± 32.5 ± 19.5 ± 4.6 2.9 4.7 4.4 4.7 4.8 4.83.4 3.2 4.7 4.5 2.5 SCD-Citrate F-80A 89.3 ± 70.0 ± 40.3 ± 40.0 ± 39.3 ±36.7 ± 29.0 ± 30.3 ± 27.3 ± 25.0 ± 17.0 ± 25.9 6.1 6.6 1.0 1.2 1.2 0.61.8 1.9 2.9 3.5 SCD-Heparin 61.4 ± 75.6 ± 61.7 ± 48.3 ± 38.6 ± 27.6 ±26.1 ± 24.0 ± 36.5 3.3 4.5 6.6 3.4 3.6 3.4 5.1 7.3 Con-Citrate 53.3 ±71.7 ± 50.3 ± 42.7 ± 48.3 ± 31.0 ± 20.0 ± 2.0 6.3 4.5 1.5 12.9 2.1 10.0Mean arterial pressure, mmHg SCD-Citrate F-40 72.2 ± 75.8 ± 67.2 ± 59.9± 54.8 ± 47.1 ± 49.5 ± 46.5 ± 35.7 ± 34.3 ± 28.4 ± 23.3 ± 4.8 2.6 4.14.2 3.9 6.4 4.5 3.7 4.9 5.3 10.1 2.7 SCD-Citrate F-80A 99.1 ± 79.6 ±48.8 ± 50.1 ± 49.2 ± 46.8 ± 39.1 ± 40.4 ± 38.8 ± 33.7 ± 22.4 ± 27 7.35.8 1.5 2.5 2.1 1.6 3.9 3.9 3.3 4.9 SCD-Heparin 72.0 ± 86.1 ± 72.6 ±60.6 ± 50.3 ± 36.5 ± 34.3 ± 26.8 ± 42.7 ± 3.3 4.4 6.5 3.1 4.4 3.6 6.38.6 0.3 Con-Citrate 64.7 ± 82.1 ± 59.3 ± 51.4 ± 44.5 ± 37.9 ± 23.3 ± 1.78.0 4.1 1.1 0.5 2.9 13.3 Systemic vascular resistance, dyn · s/cm⁵SCD-Citrate F-40 1288 ± 1119 ± 1027 ± 994 ± 1101 ± 1414 ± 1601 ± 1767 ±1701 ± 2170 ± 2856 ± 1776 ± 119 61 73 72 64 111 143 204 179 183 722 336SCD-Citrate F-80A 1881 ± 1073 ± 710 ± 784 ± 874 ± 926 ± 884 ± 1028 ±1134 ± 1088 ± 971 152 23 143 59 114 131 59 139 186 87 SCD-Heparin 1371 ±1250 ± 1268 ± 1200 ± 1412 ± 1567 ± 1552 ± 1918 ± 137 120 110 58 75 140242 533 Con-Citrate 1034 ± 1149 ± 1067 ± 976 ± 1174 ± 1375 ± 1274 111 9472 96 103 343 Pulmonary vascular resistance, dyn · s/cm⁵ SCD-CitrateF-40 141 ± 180 ± 255 ± 321 ± 393 ± 573 ± 632 ± 859 ± 935 ± 948 ± 1602 ±1067 ± 17 25 33 47 78 118 97 145 131 343 242 133 SCD-Citrate F-80A 164 ±228 ± 207 ± 281 ± 317 ± 377 ± 475 ± 543 ± 634 ± 694 ± 552 13 83 86 63 5555 61 54 49 58 SCD-Heparin 268 ± 287 ± 384 ± 525 ± 763 ± 1293 ± 1024 ±1121 ± 1504 102 51 46 58 76 243 198 291 Con-Citrate 147 ± 122 ± 404 ±602 ± 525 ± 982 ± 1199 ± 18 17 177 83 151 248 14 Pulmonary capillarywedge pressure, mmHg SCD-Citrate F-40 7.8 ± 8.5 ± 8.3 ± 7.0 ± 7.2 ± 7.2± 5.9 ± 5.9 ± 4.9 ± 6.8 ± 5.0 ± 3.5 0.7 0.9 1.0 1.1 1.1 1.1 0.9 0.8 1.02.1 2.6 SCD-Citrate F-80A 8.3 ± 11.3 ± 10.7 ± 7.3 ± 6.3 ± 5.7 ± 6.0 ±6.3 ± 6.3 ± 6.0 ± 12.0 ± 0.9 2.4 3.7 1.2 0.9 0.9 0.6 0.7 0.7 0.6 5.5SCD-Heparin 7.0 ± 8.5 ± 7.2 ± 6.6 ± 7.3 ± 6.3 ± 5.7 ± 6.8 ± 5.5 0.8 1.20.8 0.7 1.4 1.0 1.0 1.0 Con-Citrate 7.7 ± 10.7 ± 9.0 ± 7.3 ± 6.3 ± 6.3 ±8.5 ± 1.2 0.9 1.5 1.3 0.3 0.3 1.5 Renal arterial blood flow, mL/minSCD-Citrate F-40 197.4 ± 183.7 ± 193.4 ± 173.2 ± 125.1 ± 79.9 ± 69.3 ±48.5 ± 37.1 ± 37.0 ± 47.5 ± 13.5 ± 16.9 12.8 25.5 23.4 18.2 18.0 17.914.7 11.8 13.9 12.5 8.5 SCD-Citrate F-80A 152.0 ± 141.0 ± 170.7 ± 173.3± 153.0 ± 131.3 ± 103.0 ± 83.0 ± 67.3 ± 49.7 ± 30.5 ± 15.5 2.3 31.5 33.523.9 26.9 23.5 13.1 8.2 9.2 24.5 SCD-Heparin 207.0 ± 155.2 ± 152.0 ±148.5 ± 111.8 ± 53.4 ± 37.6 ± 45.8 ± 24 22.8 15.7 21.7 18.8 21.4 13.613.8 20.1 Con-Citrate 200.3 ± 157.3 ± 184.3 ± 183.0 ± 138.0 ± 69.0 ±19.0 ± 19.5 38.1 63.0 48.3 17.7 24.0 19.0 Renal vascular resistance,mmHg/min/mL SCD-Citrate F-40 0.39 ± .037 ± 0.37 ± 0.48 ± 1.05 ± 1.37 ±2.18 ± 1.93 ± 1.05 ± 0.82 ± 2.38 ± 0.03 .0.6 0.05 0.07 0.29 0.44 0.630.72 0.31 0.37 1.56 SCD-Citrate F-80A 0.67 ± 0.49 ± 0.25 ± 0.28 ± 0.30 ±0.35 ± 0.44 ± 0.50 ± 0.59 ± 1.69 ± 0.27 0.06 0.05 0.07 0.05 0.08 0.090.08 0.07 1.14 SCD-Heparin 0.39 ± 0.58 ± 0.55 ± 0.41 ± 0.63 ± 0.77 ±1.30 ± 0.78 ± 1.64 ± 0.08 0.08 0.11 0.04 0.20 0.16 0.37 0.23 0.30Con-Citrate 0.30 ± 0.52 ± 0.33 ± 0.26 ± 0.28 ± 0.67 ± 0.75 0.02 0.120.08 0.05 0.04 0.31

Cardiac outputs (CO) were also assessed. As depicted in FIG. 5B, CO wassignificantly higher (p<0.02) in the SCD-C groups. This increase in COwas not due to differences in left ventricular filling pressures, sincepulmonary capillary wedge pressures were similar in all three groups.Rather, the increase in CO in the SCD-C groups was associated with lowerlevels of systemic vascular resistance (SVR; p<0.03; FIG. 5C) andpulmonary vascular resistance (PVR; p<0.001; FIG. 5D). Notably, theSCD-C, F-80A group consistently showed the most improvement in cardiacout and also had lower SVR, PVR, and renal vascular resistance (FIG. 5E)when compared to the other groups.

As a quantitative measure of the systemic capillary leak induced bybacterial sepsis, changes in hematocrit (HCT) were assessed. As depictedin FIG. 5F, the SCD-H group had a higher rate of HCT increase,reflective of larger rates of volume loss from the intravascularcompartment. In comparison, HCT levels plateaued after 6 hours in theSCD-C groups. Notably, the SCD-C, F-80A group showed the most protectionto the bacterially activated systemic capillary leak.

Renal parameters were also assessed. As shown in FIG. 6, the SCD-Cgroups exhibited much better renal function than the SCD-H group asreflected in the lower BUN (p<0.02) and serum creatinine levels(p=0.007). Renal blood flow (RBF) was also much better preserved in theSCD-C, F-80A group as compared to the SCD-H group (p<0.05). Furthermore,the SCD-C, F-80A group also exhibited must higher urine output (p<0.05).

The improved cardiovascular and renal parameters observed with the SCD-Cgroups translated to longer survival time. As shown in FIG. 7, thecitrate-treated animals survived 8.8±0.4 hours compared to 6.4±0.3 hoursfor the SCD-H animals (p=0.0002). Notably, the SCD-C, F-80A group hadthe longest survival times (11.5, 10, and 9.5 hours), as shown in FIG.8.

Only those animals treated with a combination of the SCD device andcitrate exhibited improved cardiovascular parameters and organ function.The Con-citrate group of animals treated with a single hemofiltercartridge with citrate anticoagulation but without the SCD devicedemonstrated similar cardiovascular parameters as the SCD-H group, witha average survival time of 6.5±0.5 hours. Thus, both the SCD cartridgeand the citrate anticoagulation protocol were required to provide asurvival advantage. Furthermore, it was found that the surface area forsequestration can have a profound effect on alleviating complicationsrelating to sepsis and in prolonging survival time post infection.

B—Observations of Leukocyte Sequestration and Activation

To assess the sequestration of activated leukocytes along the SCDmembranes, the SCD cartridges were processed for histologic evaluationat the conclusion of the porcine sepsis study. The light microscopyfindings depicted in FIG. 9 clearly showed leukocyte attachment andaggregation along the outer surface of the SCD membranes. To determinethe amount and type of adherent leukocytes, the devices were processedand cells eluted off the membrane at the end of the treatment period.The number of white blood cells (WBCs) eluted off the SCD-H and SCD-C,F-40 cartridges were 6.44±3.4×10⁸ and 1.72±1.20×10⁸ cells (FIG. 10A)(p<0.05), respectively, indicating that citrate anticoagulation reducedthe number of adherent leukocytes. Furthermore, the distributions ofeluted cells were 79±5% neutrophils and 21±4% monocytes in the SCD-Hgroup as compared to 55±4 neutrophils and 30±5% monocytes in the SCD-C,F-40 group (FIG. 10B). Surprisingly, an average of 1.88±1.21×10⁷ cellswere eluted off from the cartridges of the SCD-C, F-80A group (FIG.10A), which was about ten fold lower than the average number of elutedcells from the SCD-C, F-40 group. Thus, even though the substantiallylarger membrane surface area of the F-80A might have led to increasedretention of leukocytes, the SCD cartridge's efficiency in deactivatingleukocytes apparently led to a dramatic reduction in leukocyte retentionby the end of the procedure. An average of 8×10⁶ cells were eluted fromthe cartridges of non-septic control animals (n=2), suggesting that mostof the cells that were sequestered in the cartridges of the SCD-H andSCD-C groups were activated leukocytes. The SCD-C group had fewer than2×10⁴ cells eluted from lumens of the cartridges with luminal bloodperfusion.

In order to determine whether the SCD cartridge with citrateanticoagulation can influence the activity of neutrophils in thesystemic circulation, biomarkers of neutrophil activation were assessed.Activated neutrophils release various enzymes in response to invadingmicrobes or tissue injury. Since the dominant enzyme released fromneutrophil granules is myeloperoxidase (MPO) (Klebanoff, S. J., et al.,(2005) LEUKOC. BIOL. 77(5): 598-625), blood MPO levels reflect the levelof neutrophil activation. As depicted in FIG. 11A, plasma MPO levels inthe SCD-C groups were significantly lower compared with the SCD-H group,reflective of a lower level of activated neutrophils. Furthermore, theSCD-C, F-80A group showed the lowest level of MPO. Systemic circulatingneutrophil activation was also assessed by measuring the amount of CD11bexpression on circulating neutrophils. CD11b is a membrane proteininvolved in the adherence of leukocytes to activated endothelium at thesite of inflammation (Fan, S. T., et al., (1993) J. IMMUNOL., 150(7):2972-2980). As depicted in FIG. 11B, the amount of CD11b expression oncirculating neutrophils was dramatically decreased in the SCD-C groupscompared to the SCD-H groups (p=0.03), indicating a lower level ofneutrophil activation.

To further assess the immunomodulatory effect of the SCD cartridge andregional citrate coagulation, systemic cytokine levels were evaluated.Serum levels of various cytokines including IL-1β, IL-6, IL-8, IL-10,TNF-α and IFN-γ were not significantly different between the SCD-H andthe SCD-C groups, although the pro-inflammatory cytokines IL-1β and IL-8appeared to be slightly higher in the SCD-H group. Since the SCD devicealso sequesters monocytes, PBMCs were isolated and assessed for cytokinerelease. Prior to sepsis induction, PBMC release of TNF-α and IL-8 inresponse to LPS were 2.1±1.8 and 6.5±2.8 pg/10⁶ cells, respectively, inthe SCD-H group; in the SCD-C group, the release was 5.1±0.9 and18.7±8.1 pg/10⁶ cells, respectively. At 6 hours post sepsis, PBMCrelease of TNF-α and IL-8 in response to LPS was significantly lower inthe SCD-C groups as compared to the SCD-H group (p<0.05) (FIGS. 12A and12B). These results indicated that the overall pro-inflammatory cytokineprofile in the septic state was dampened in the SCD-C groups. Again, itappeared that the SCD device having a membrane surface area of 2.5 m²had the greatest immunomodulatory effect.

Previous studies have reported that the lung was the first organtargeted for activated leukocyte sequestration and infiltration afterendotoxemia or sepsis (Welbourn, C. R. et al., (1992), BR. J. SURG.,79(10): 998-1003; Andonegui, G., et al., (2009), J. CLIN. INVEST.,119(7): 1921-1930). Thus, we evaluated the effect of the SCD device andcitrate anticoagulation on the sequestration of activated leukocytes inlung tissues. As demonstrated in FIG. 13, a significant decrease inCD11b-labeled cells in the lung was observed in the SCD-C group comparedto the SCD-H group. Further, a histomorphometric analysis showed thatthe ratios of percent CD11b-positive area by percent DAPI-positive areain the SCD-C group and SCD-H group were 0.114±0.21 versus 0.334±0.052(p=0.007), respectively (FIG. 14). Together, these results indicated areduced lung sequestration of activated leukocytes in animals treatedwith the SCD device and citrate.

White blood cell (WBC) kinetics may also provide insights into themanner in which the SCD device may influence leukocyte response toinfection. To determine the kinetics of the circulating pool ofleukocytes in the SCD-H and SCD-C groups, absolute WBC and neutrophilcounts were measured (FIG. 15). Both the SCD-H and SCD-C, F-40 groupsreached a nadir of 1125±240 and 1094±166 neutrophils/mm³ at 3 hours postsepsis induction, respectively. These groups did not reach absoluteneutropenia (defined as counts below 500) due to an increase in immatureneutrophils from the bone marrow, as determined by manual examination ofblood smears, beginning at 3 hours post sepsis induction. Notably, theSCD-C, F-80A, group consistently exhibited a low neutrophil countreaching a nadir of 457±77 at 6 hours. This was due to a markedlydiminished release of immature neutrophils from the bone marrow,suggesting that the SCD device with a larger surface area may functionto alter the kinetics of bone marrow release of immature neutrophils.The Con-citrate F-40 group had a similar decline and rebound ofleukocyte counts as the SCD-H F-40 group, whereas the NS-control animalstended to have neutrophilia, with neutrophil counts rising fromapproximately 4,000 to 14,000 over the 8-hour evaluation period.

Under septic conditions, activated neutrophils have an increasedlifespan with a delay in apoptosis. The apoptotic potential of thecirculating and adherent leukocytes isolated from the SCD-C groups wasassessed. As shown in FIG. 16, the SCD-C, F-80A group had a highernumber of apoptotic circulating neutrophils as compared to the SCD-C,F-40 group, suggesting that this SCD device with the larger membranesurface area decreased the activation state of circulating neutrophils.On the other hand, the SCD-C, F-80A group had fewer apoptoticSCD-cartridge-adherent neutrophils, suggesting that this SCD deviceselectively sequestered activated neutrophils thus removing them fromthe circulating pool.

Together, the above results demonstrated the efficacy of the SCD devicecombined with citrate in ameliorating cardiovascular instability,reducing renal dysfunction, and improving survival time in a porcinemodel of septic shock. More importantly, these results demonstrated thata SCD cartridge having larger sequestration area is more effective inalleviating the complications associated with sepsis.

Example 2. In Vitro Studies of Leukocyte Sequestration and Deactivation

This example describes in vitro experiments to evaluate the effect ofthe SCD device on leukocyte sequestration and activation.

(I) Methods and Materials

A—In Vitro Assessment of Leukocyte Interaction with the Membrane of aSCD Cartridge

A custom microscopic flow chamber system was set up to enablemicroscopic analysis of leukocyte interaction with the SCD membrane. Theflow chamber consisted of a polycarbonate housing with an inlet andoutlet for perfusion. A polysulfone membrane was affixed to thepolycarbonate block with a gasket which directed shear flow. Thethickness of the gasket (100 μm) along with the length (2 cm) and thewidth of the channel (1.5 mm) determined the volume of the flow chamber.Microscopic imaging was accomplished through an optical window made upof a cover glass affixed to the bottom of the polycarbonate block.Either isolated blood or purified leukocytes were used for this study.

Isolated blood was prone to activation from excessive handling. Thus, 5mL of fresh heparinized porcine blood was minimally manipulated prior tothe flow chamber study. Briefly, leukocytes were fluorescently labeledusing 50m/mL of Hoechst 33342 dye. Further, the leukocytes wereactivated by adding 1 μg/mllipopolysaccharide (LPS) directly to theblood samples. Similarly, 125 μL of Anticoagulant Citrate DextroseSolution USP (ACD) Formula A (Baxter) was added to 5 mL of isolatedblood and ionized calcium levels were measured prior to microscopic flowanalysis with i-stat EG-7+ cartridges. Blood passed through the flowchamber at a rate of 20 μL/min with calculated shear forces between 1-10dynes/cm². For each isolated blood sample, sequences were acquired intriplicate.

Microscopic analysis of cell capture events was accomplished usingeither a Zeiss Axiovert 200M or Axio-Observer epifluorescence microscopeequipped with a microscope stage-top incubator to control environmentaltemperature and CO₂ content. Fluorescence images were acquired witheither a Zeiss MRm3 or an Icc1 camera at a frequency of 1 frame/secondfor 5 minutes, for analysis of leukocyte/membrane interaction, and at 1frame/minute for 1 hour sequences, for analysis of long term leukocyteattachment. Frame by frame evaluation of leukocyte rolling, attachmentand detachment of leukocytes was carried out to determine the totalnumber and duration of these phenomena. An attachment event was definedas when a leukocyte appeared in the same location for multiple frameswithin a sequence. Detachment was defined as release events associatedwith previously defined attached leukocytes. Rolling events were definedby identifying the same leukocyte in multiple sequence frames within asequence where the leukocyte was not in same exact location, but inclose proximity to the prior location.

B—Assessment of In Vitro Leukocyte Activation

Heparinized human whole blood was added to tubes with or withoutlipopolysaccharide (LPS) (10 μg/mL) orformyl-Methionyl-Leucyl-Phenylalanine (fMLF, 50 nM). Citrateanticoagulation was achieved by adding citrate dextrose solution (ACD)to the tubes (Damsgaard, C. T., (2009) J. IMMUNOL. METHODS, 340(2):95-101; Wutzler, S., (2009) J. TRAUMA, 66(5): 1273-1280). The release ofIL-6, IL-8, or IL-10 was measured using commercially available ELISAkits from R&D Systems. The release of elastase was measured using acommercially available ELISA kit from Bender MedSystems. The release oflactoferrin was measured using a commercially available ELISA kit fromEMD Chemicals. The iCa levels were measured using an I-STAT reader andwere confirmed to be ≤0.25 mM and 1.25 mM in the citrate treated ornontreated samples, respectively. Samples were incubated for varioustimes at 37° C. and 5% CO₂. CD11b activation was measured using anFITC-conjugated mouse anti-human antibody (AbD Serotech) and evaluatedon an Accuri C6 flow cytometer.

(II) Results and Discussion A—Observation of Leukocyte Parameters

To assess the interactions of leukocytes and the SCD polysulfonemembranes, a customized flow chamber with video microscopy was set up.The addition of citrate lowered blood iCa level from 1.32±0.05 mmol/L to0.32±0.05 mmol/L. Analysis of leukocyte attachment events confirmed thatLPS activation of the leukocytes in the absence of citrate significantlyincreased leukocyte attachment to polysulfone membranes during shearflow (p<0.05, FIG. 17). In citrate-treated, low ionized calcium flowchambers, a statistically significant decrease in leukocyte attachmentwas observed (p<0.05), suggesting that leukocyte adhesion to polysulfonemembranes may be ionized calcium dependent. These results wereconsistent with the ex vivo data in the above-described sepsis porcinemodel, in which citrate-treated membrane cartridges had fewer adherentleukocytes at the end of the studies. In addition, preliminary analysisof 1 hour sequences demonstrated far fewer persistent leukocyte adhesionevents for LPS and citrate treated blood compared to blood treated withLPS only. However, there was an observed increase in rolling events forthe LPS and citrate treated blood. This suggested a catch and releasephenomena when leukocytes interact with the polysulfone membrane in thepresence of citrate.

Experiments were carried out to assess the effects of citrate-promotedreductions in blood iCa on leukocyte activity. Specifically, an in vitrowhole blood assay system was utilized (Damsgaard, C. T., (2009) J.IMMUNOL. METHODS, 340(2): 95-101; Wutzler, S., (2009) J. TRAUMA, 66(5):1273-1280) to assess the effects of lowered blood iCa levels onleukocyte cytokine production (IL-6, IL-8, IL-10) and the release ofpreformed inflammatory proteins from neutrophil exocytotic vesicles(lactoferrin, elastase). The results are summarized in Table 6.

TABLE 6 Effect of citrate on leukocyte activation parameters IL-6 IL-8IL-10 Lactoferrin Elastase CD11b (ng/mL) (ng/mL) (ng/mL) (mg/mL) (mg/mL)(MFI × 10³) n = 7 n = 5 n = 4 n = 4 n = 5 n = 3 Baseline Heparin 0.18 ±0.0 ± 0.11 ± 8.47 ± 2.73 ± 22.55 ± 0.04 0 0.07 1.54 0.29 1.06 Citrate0.38 ± 0.59 ± 0.01 ± 1.67 ± 0.94 ± 7. 32 ± 0.15 1.51 0.01 0.29* 0.14§0.47§ Stimulated (LPS, fMLF) Heparin 65.42 ± 34.18 ± 3.74 ± 12.42 ± 4.52± 53.43 ± 19.77 6.66 0.94 1.08 0.54 3.12 Citrate 28.99 ± 3.45 ± 2.06 ±3.43 ± 0.91 ± 28.72 ± 7.60* 2.30† 0.84† 0.18§ 0.28** 2.95§ *p < 0.05; †p< 0.02; **p < 0.005; §p < 0.002, as determined with paired t-testbetween heparin and citrate groups.

As shown in Table 4, lowering iCa with citrate inhibited the release ofcytokines (IL-6, IL-8, IL-10) and neutrophil exocytotic proteins,suggesting that a low iCa environment promoted the deactivation ofleukocytes.

Example 3. Use of SCD Device During Cardiopulmonary Bypass Surgery

Systemic Inflammatory Response Syndrome (SIRS) can occur in associationwith cardiopulmonary bypass (CPB) surgery, resulting in multiple organdysfunction (MOD). Activated neutrophils have been implicated as majorinciting factors in this process. This example describes in vitro and invivo experiments that evaluate the effect of SCD cartridges for useduring CPB surgery. The results demonstrate that the usage of SCDcartridges may disrupt the systemic leukocyte response during CPBsurgery, leading to improved outcomes for CPB-mediated MOD.

(I) Background

Leukocytes, especially neutrophils, are major contributors to thepathogenesis and progression of many clinical inflammatory disorders,including systemic inflammatory response syndrome (SIRS), sepsis,ischemia/reperfusion injury, acute respiratory distress syndrome (ARDS)and acute kidney injury (AKI). Cardiac surgical advances have beendependent upon the techniques for cardiopulmonary bypass (CPB). It hasbeen recognized that a systemic inflammatory response occurs inassociation with CPB, resulting in multiple organ dysfunctions (MOD)following surgery. Multiple insults during CPB have been shown toinitiate and extend this inflammatory response, including artificialmembrane activation of blood components (membrane oxygenator), surgicaltrauma, ischemia-reperfusion injury to organs, changes in bodytemperature, blood activation with cardiotomy suction, and release ofendotoxin. These insults promote a complex inflammatory response, whichincludes leukocyte activation, release of cytokines, complementactivation, and free-radical generation. This complex inflammatoryprocess often contributes to the development of acute lung injury, acutekidney injury, bleeding disorders, altered liver function, neurologicdysfunction, and ultimately MOD.

The mechanisms responsible for MOD following CPB are numerous,interrelated and complex, but growing evidence suggests a critical rolein the activation of circulating blood leukocytes, especiallyneutrophils in the development of ARDS in CPB-induced post-pumpsyndrome. Sequestered and activated neutrophils migrate into lungtissue, resulting in tissue injury and organ dysfunction. The importanceof activated leukocytes and microvascular dysfunction has also beendemonstrated to be important in acute kidney injury.

In this regard, the use of leukocyte depleting filters within anextracorporeal blood circuit during CPB has been developed and evaluatedin preclinical animal models and clinical studies. While filters removeleukocytes in vitro, they do not appear to consistently depleteleukocyte concentrations in vivo. The majority of papers reported nosignificant reduction in circulating leukocytes, a conclusion similarlydrawn by meta-analysis. Acknowledgement of “filter exhaustion,” aprogressive decrease in leukocyte reduction efficiency during CPB hasbeen repeatedly observed during experimental evaluation.

The instant invention utilizes a biomimetic membrane called theselective cytopheretic device (SCD) and regional citrate anticoagulationto promote a decrease in activated leukocytes in animals and patientssuffering from acute inflammation. Early pre-clinical and clinicalresults, suggest that the device ameliorates the MOD effects of SIRS andimpacts the mortality rate of multiorgan failure in intensive care unit(ICU) patients. Results described herein demonstrate that the SCDreduces the circulating level of neutrophils and reduces markers ofneutrophil activation, both in vitro and in vivo.

(II) Methods and Materials A—Selective Cytopheretic Device (SCD)

The SCD tested was a polycarbonate housing containing porous polysulfonehollow fibers with an inner diameter of 200 μm, a wall thickness of 40μm, and a molecular weight cutoff of 40 to 50 kDa. Blood flow wasdirected to the extracapillary space (ECS). The SCDs used had outermembrane surface area (SA) of 2.2 m² and 2.6 m², and surface area/innervolume (SA/IV) ratios of 486 cm⁻¹ and 508 cm⁻¹, respectively. The SCDswere supplied by CytoPherx, Inc. (Ann Arbor, Mich.).

B—In Vitro Blood Circuit Studies

In vitro blood circuit studies were initiated to compare two leukocytereducing membrane systems, the Pall Leukogard LGB (Ann Arbor, Mich.) andthe SCD device in a series of 10 paired studies. Fresh, heparinizedbovine blood (5-6L) was collected in a 7L silicone drain bag (B BraunMedical Inc. Bethlehem, Pa.) with 90,000 IU sodium heparin (ClipperDistributing LLC, Saint Joseph, Mo.) and divided evenly into twoidentical drain bags, which served as reservoirs for two separate bloodcircuits, each to test the respective device. The in vitro bloodcircuits utilized FDA approved Tygon lines (Cole-Parmer, Vernon Hills,Ill.). The circuits were set up to monitor temperature with type Tthermocouples, and pressure measurements with a 4 channel 90XL (MesaLabs, Lakewood, Colo.), pre- and post-device during perfusion. Bothblood reservoirs were warmed in the same water bath (34.5° C.) to insureidentical heating behavior, and a handheld IR-pyrometer was employed tomeasure internal temperatures (approximately 31° C.) within each devicetested. Peristaltic blood pumps (Fresenius 2008H, Walnut Creek, CA)maintained a constant flow rate of 300 mL/min in both circuits.

Blood samples were obtained every 15 minutes to measure total whitecell, neutrophil, and platelets as previously described, as well as forother assays. For plasma myeloperoxidase (MPO) and free hemoglobin (Hgb)analysis, blood samples were immediately cooled and centrifuged free ofcells. Plasma hemoglobin concentration was chemically determined using acolorimetric assay with 3,3′, 5,5′, tetramethylbenzidine (TMB), and MPOwas measured by ELISA. At the end of the experiment, the circuit wasdisconnected and normal saline flushed continuously through theextracapillary space (ECS) of the SCD until fluid was free of visibleblood, and then the SCD was eluted to quantify adherent cells aspreviously described. A similar process was also conducted to elute LGBfilters.

C—In Vivo Cardiopulmonary Bypass Model

Wisconsin calves (100-110 kg) were premedicated with atropine (0.04mg/kg), and ketamine (25 mg/kg) administered by intramuscular (IM)injection, and then anesthetized with 5 mg/kg of thiopental. Afterintubation with an endotracheal tube (Mallinckrodt Company, Mexico City,Mexico), ventilation was established with a volume cycle ventilator.Anesthesia was maintained by continuous infusion of 5 mg/kg/h ofthiopental and 20 μg/kg/h of fentanyl. Muscle relaxation was inducedwith 0.2 mg/kg of pancuronium followed by intermittent reinjections at0.1 mg/kg. Polyethylene monitoring lines were placed in the externaljugular vein and the femoral artery and vein. Median sternotomy wasperformed. A 16 to 20 mm Transonic perivascular flow probe was placed onthe main pulmonary artery, and Millar microtip pressure transducers wereplaced in the pulmonary artery and left atrium. Prior to initiatingcardiopulmonary bypass, baseline pulmonary artery pressure and flow rateand left atrial pressure readings were taken for determination ofcardiac output. After systemic heparinization (300 U/kg), an 18FMedtronic DLP arterial cannula was placed in the left carotid artery anda 24F Medtronic DLP single-stage venous cannula was placed in the rightatrium.

The CPB circuit was primed with 1,000 mL of lactated Ringer's solutionand 25 mEq of NaHCO₃. The circuit consisted of a Sarns roller bloodpump, a Medtronic Affinity hollow fiber oxygenator with integral heatexchanger, and a cardiotomy reservoir. A Medtronic Affinity 38-μm filterwas placed in the arterial limb to capture particulate debris. The leftventricle was vented using a 12-Ga Medtronic standard aortic rootcannula with vent line connected to a Sarns roller pump and thecardiotomy reservoir. Cardiopulmonary bypass was initiated, ventilationwas discontinued, and systemic perfusion maintained at 2.4 L/min/m² bodysurface area. Moderate perfusion hypothermia (32° C. rectal temperature)was used, and mean aortic pressure kept at 60-80 mmHg by modification offlow and intravenous phenylephrine infusion (0-2 μg/kg/min). Theascending aorta was cross clamped. CPB was maintained for 255 minutes.

Three groups of animals were evaluated: CPB circuit without SCD, CPBcircuit with SCD, and CPB circuit with SCD with citrate/calcium regionalperfusion to provide a low ionized calcium (iCa) blood environment onlyalong the SCD circuit. The SCD circuit blood flow was controlled at 200mL/min with an AK12 blood pump system (Gambro). Citrate/calcium infusionwas based upon well developed clinical protocols for citrate regionalanticoagulation, as previously described.

Similar to the in vitro blood circuit studies, for all sample timessystemic blood was used to assess CBCs. The SCD or LGB was routinelyremoved at T=225 minutes, with a final blood sample taken 15 minutesafter removal to evaluate post therapy dynamics. Total manual white cellcounts were determined using the Unopette system (BD Biosciences) andmanual differentials were determined from blood smears after ethanolfixation and Wright stain (Richard-Allen Scientific). After each study,if a SCD or LGB was used, adherent cells were eluted and quantified aspreviously described.

D—Statistical Analysis

Analysis of variance (ANOVA) was conducted for all studies withstatistical significance of p<0.05.

(III) Results and Discussion A—In Vitro Blood Circuit Studies

The temperature of the blood was similar between the SCD and LGBcircuits throughout the study, averaging 31.1±0.4° C. and 31.1±0.3° C.,respectively. The pressure profile across the devices were 92.0±49.1 and29.2±16.2 mmHg for pre- and post-SCD with a pressure drop of 62.9±39.8,and 98.8±71.5 and 40.1±17.1 pre- and post-LGB, with a pressure drop of31.3±3.9 mmHg. The variability in pressures was related to differencesin the hematocrit of blood in the circuit, which averaged 31.1±3.9%.

The total white cell counts for the LGB circuits dropped by greater than50% within the first 15 minutes and remained steady to the end of theexperiment. This decline is largely the result of a more than an 80%drop in circulating neutrophils. The SCD circuits showed a substantial,but smaller drop in total white cells and neutrophils during theexperiment, with the neutrophil counts declining between 40% and 60%.Differential white blood cell counts from each device were evaluated.Monocyte and eosinophil concentrations also declined, but due to theirlow percentages in circulating blood, accurate quantification waschallenging. A substantial decline in the number of platelets wasobserved, with the SCD and LGB in particular, displaying a relativeplatelet reduction of greater than 80% at 15 minutes. However, in bothcases the platelet count rebounds to a level equivalent to approximately50% of the platelet counts enumerated prior to beginning the experiment.

B—In Vitro Blood Circuit Device Elution

The total number of cells eluted from LGB and SCD were counted. Twice asmany cells were recovered from LGB than the SCD. The percentage ofneutrophils, monocytes, and eosinophils in the closed circulation loopthat were recovered from each device were calculated. The total numberof each leukocyte population recovered from each device was divided bythe total number of each leukocyte population present in blood prior tothe initiation of each experiment. The Mean±SEM for neutrophils,monocytes, and eosinophils are shown for 10 SCD and 10 LGB. Neutrophilsoutnumbered monocytes roughly 2 to 1, while eosinophils were present ata variable and much smaller number and percentage from both leukocytefilters. More neutrophils and monocytes were eliminated from LGB versusSCD.

Total cell numbers remaining in the blood at the termination of eachexperiment were added to the cell numbers eluted from the device andcompared with the number of cells present in the blood sample at thebeginning of the experiment. The difference in these numbers is reportedas the “change of total cell number” and is most likely to indicate thenumber of cells destroyed during the four hour circulation experiment.Significantly more cells were unaccounted for in the circuits employingthe LGB than in the case of the SCD (P<0.05).The data are presented asthe mean±SEM of 10 paired experiments.

C—In Vitro Blood Circuit Blood Biocompatibility

Neutrophil released myeloperoxidase (MPO) activity was assayed as themean±SEM for SCD (N=8), and for LGB (N=10) in μg/ml. Plasma MPO activitywas significantly higher for the LGB relative to the SCD, with a peak atthe first sampling time after circuit initiation (7.45±3.02 μg/mL) andcontinued to be elevated for the remainder of the experiment (p<0.05).SCD circuit MPO values remained below 0.4 μg/mL at all times. Freehemoglobin (Hgb) in plasma, a measure of hemolysis is also assessed, asthe mean±SEM for LGB (N=10) and SCD (N=10) in mg/mL, with a peak at thefirst sampling time after circuit initiation (0.06±0.04 mg/mL) andelevated levels throughout. SCD circuit free hemoglobin values remainedbelow 0.005 mg/mL at all times.

D—In Vivo Bovine Calf Model of CPB

Systemic white blood cell (WBC) counts are assessed for the CPB in vivobovine studies. In the CPB No SCD control group, WBC increased above thebaseline level counts after 90 minutes and peaked with nearly double thebaseline WBC. For device treated groups, WBC counts decreased in thefirst hour of CPB. In the SCD heparin treatment group, following thisinitial reduction, the WBC gradually increased after 60 minutes, andthroughout CPB, with a sharp raise after removing SCD (routinely att=225 min) for the final measurement 15 minutes thereafter. Similarresults were observed when LGB was placed in the circuit rather than theconventional arterial line filter (data not shown). In SCD citrategroup, WBCs were low throughout CPB, and even after the SCD was removed.

Quantification of the neutrophil population during cardiopulmonarybypass (CPB) surgery without a SCD showed an approximate 5-fold rise inthe systemic levels. SCD treatment with only systemic heparincoagulation during CPB dramatically reduced the systemic neutrophilconcentration during the first 120 min, but was followed by a steadyrise until SCD removal (routinely at t=225 min), with a larger increase15 minutes after SCD removal. SCD with regional citrate during CPBresulted in a systemic neutrophil concentration approximately 75% lowerthan the pre-SCD level, which persisted throughout CPB, and remained low15 minutes after SCD removal.

At the conclusion of SCD therapy, SCD were thoroughly washed and boundleukocytes were eluted and enumerated. On average 8×10⁷ and 1.63×10⁹leukocytes were eluted from the SCD employing regional citrate orsystemic heparin, respectively. Eluted cells were of the granulocyticlineage independent of the use of regional citrate, on averageconsisting of approximately 80% neutrophils, 20% monocytes, and variableamounts of eosinophils, typically <2%, similar to distributions reportedin in vitro blood circuit studies. Preliminary results from thequantification of immature neutrophils by manual counts demonstrate atrend of low counts for the SCD-Citrate group at the end of 240 minutesof CPB (230, 0 per μL, n=2) whereas SCD-Heparin (1630, 6300, 1390 perμL, n=3), No SCD (160, 2660 per μL, n=2) and LGB (1760, 3880 per μL,n=2) groups all have cases of increased amounts of immature neutrophils.

E—Discussion

CPB promotes SIRS often resulting in MOD. This inflammatory disorderarises from multifactorial processes, but circulating leukocyteactivation is postulated to play a central role. Therapeuticinterventions directed toward leukocyte depletion during CPB have beenevaluated both in pre-clinical and clinical studies. The results havebeen inconsistent with regards to reducing circulating leukocyte countsand alleviating progression to MOD.

An in vitro test circuit was developed to assess leukocyte depletion ina circulating heparinized blood circuit between 31° C. and 34.5° C. andcomparable blood flow rates of 300 ml/min. When integrated into theblood circuit, both the LGB and SCD prompted a significant reduction incirculating white blood cell and neutrophil counts with the LGB grouphaving a greater effect to lower WBC counts compared to the SCD. Thisreduction in leukocyte counts in the LGB group compared to the SCD groupwas due to both a higher degree of sequestration in the device (elutedcells), and a higher degree of destruction of leukocytes (by massbalance). Destruction of cellular elements within the blood wasreflected in the higher free hemoglobin and MPO levels in the LGB versusSCD. Platelet dynamics with over an 80% reduction within the first 15minutes followed by a recovery to 50% of the pre-study plateletconcentration, are suggestive of rapid initial phase of platelet bindingto circuit components, followed by subsequent release.

To further assess the influence of the SCD to lower circulatingleukocyte counts, a bovine model utilizing CPB was examined. CPBperformed without SCD demonstrated a small, but not statisticallysignificant reduction of WBC counts in the first 60 minutes of CPBperfusion most likely due to non-specific attachment along theartificial membranes and blood tubing of the perfusion circuit. After 60minutes, the WBC counts increased two-fold, and neutrophils increased upto five-fold relative to starting values. When the SCD was placed in thecircuit utilizing systemic heparinization, leukocyte reduction wasachieved for 2 hours, but led to a large increase in neutrophils atlater time points and following SCD removal. When the SCD perfusioncircuit was regionally perfused with citrate to lower ionized calcium to0.25 to 0.40 mM, leukocyte and neutrophil counts remained low throughoutCPB, even after removal of the SCD (routinely at t=225 min) for thefinal measurement 15 minutes after SCD removal.

The WBC and neutrophil kinetics in these bovine studies also provideinsight into the manner in which SCD treatment may influence theleukocyte response to CPB. The number of neutrophils sequestered in theSCD was approximately 10⁸ cells, a small percentage of the circulatingand marginated pool. However, the magnitude of neutrophil release frombone marrow and marginated stores in response to the systemic insult ofCPB was blunted with SCD, especially with regional citrate infusion,suggesting that SCD-C treatment may alter the kinetics of neutrophilapoptosis and/or signals required for recruitment of neutrophils frommarginated or bone marrow pools.

Further, the finding that the number of leukocytes eluted from the SCDduring citrate infusion was 10-fold less than in the heparin condition,while maintaining lower leukocyte concentration in blood suggests thatthe low-iCa environment may promote the adhesion of activatedleukocytes, followed by release after a time period of sequestration anddeactivation. The kinetics of this “catch and release” phenomenon issupported with published and ongoing studies utilizing in vitro shearchambers. These in vitro and ex vivo studies suggest that the SCDdevices of the invention may ameliorate the natural progression of SIRSby blunting the systemic leukocyte response leading to improvedcardiovascular stability, respiratory performance and renal function.This study demonstrates a preventative therapeutic approach toameliorate CPB promoted leukocyte response and lessen progression toMOD. The in vitro and ex vivo data provided herein demonstrates thesafety and efficacy of the SCD for CPB applications.

Example 4. Exemplary SCD Cartridge for Use in Treating an InflammatoryCondition in a Subject

To demonstrate the efficacy of the SCD cartridges of the invention,subjects (for example, porcine animal model or a human subject) withvarious inflammatory conditions may be treated with a SCD device listedbelow in Table 7 using the protocols described above to improvecardiovascular and/or renal parameters.

TABLE 7 Exemplary SCD Cartridges Device ECS SA (m²) ECS SA (cm²) ECSFill (cm³) SA/V (cm⁻¹) 1 0.98 9800 130 75 2 2.5 25000 250 100 3 1.2512500 125 100 4 2.5 25000 125 200 5 2.5 25000 109 230 6 2.5 25000 94 2677 5 50000 93 536 8 5 50000 125 400 9 6.7 67000 125 537 10 10 100000 125800

The SCD cartridges of the invention may also be adapted for treatingsmall subjects (for example, pediatric patients) with inflammatoryconditions. Table 8 depicts various SCD cartridges that may be useful insuch applications.

TABLE 8 Exemplary SCD Cartridges ECS SA ECS SA ECS Fill SA/V Device (m²)(cm²) (cm³) (cm⁻¹) 1 - 1.5 cm case; 200 μm fibers 0.17 1700 9 185 2 -1.5 cm case; 100 μm fibers 0.35 3500 9 392 3 - 1.5 cm case; 75 μm fibers0.47 4700 9 530 4 - 1.5 cm case; 50 μm fibers 0.70 7000 9 784 5 - 2.5 cmcase; 200 μm fibers 0.49 4900 25 199 6 - 2.5 cm case; 100 μm fibers 0.989800 25 399 7 - 2.5 cm case; 75 μm fibers 1.30 13000 25 526 8 - 2.5 cmcase; 50 μm fibers 1.96 19600 25 797

INCORPORATION BY REFERENCE

The entire disclosure of each of the publications and patent documentsreferred to herein is incorporated by reference in its entirety for allpurposes to the same extent as if each individual publication or patentdocument were so individually denoted.

EQUIVALENTS

The invention may be embodied in other specific forms without departingfrom the spirit or essential characteristics thereof. The foregoingembodiments are therefore to be considered in all respects illustrativerather than limiting on the invention described herein. Scope of theinvention is thus indicated by the appended claims rather than by theforegoing description, and all changes that come within the meaning andrange of equivalency of the claims are intended to be embraced therein.

What is claimed is:
 1. A cartridge for treating activated leukocytes,activated platelets, or both activated leukocytes and activatedplatelets, comprising: (a) a rigid housing defining an inner volume(IV), a fluid inlet port and a fluid outlet port, wherein the innervolume is in fluid flow communication with the fluid inlet port and thefluid outlet port; and (b) a solid support disposed within the housingand defining a fluid contacting surface with a surface area (SA) capableof sequestering an activated leukocyte and/or an activated platelet ifpresent in a body fluid entering the housing via the fluid inlet port,wherein the SA/IV ratio is greater than 150 cm⁻¹ and the solid supportis disposed within the housing at a packing density in the range from20% to 65%.
 2. The cartridge of claim 1, wherein the SA/IV ratio is inthe range from 150 cm⁻¹ to 1,500 cm⁻¹.
 3. The cartridge of claim 2,wherein the SA/IV ratio is in the range from 300 cm⁻¹ to 1,000 cm⁻¹. 4.The cartridge of claim 3, wherein the SA/IV ratio is in the range from400 cm⁻¹ to 800 cm⁻¹.
 5. The cartridge of claim 2, wherein the SA/IVratio is in the range from 200 cm⁻¹ to 600 cm⁻¹.
 6. The cartridge ofclaim 1, wherein the solid support is a membrane.
 7. The cartridge ofclaim 6, wherein the membrane is porous. 8-13. (canceled)
 14. Thecartridge of claim 1, wherein the SA is in the range of from 0.1 m² to5.0 m². 15-22. (canceled)
 23. The cartridge of claim 1, wherein thefluid inlet port and the fluid outlet port are dimensioned to permit aflow rate through the housing in a range from 10 cm³/minute to 8,000cm³/minute. 24-32. (canceled)
 33. A method for processing an activatedleukocyte, an activated platelet, or both an activated leukocyte and anactivated platelet contained within a body fluid, the method comprising:(a) providing a cartridge comprising (i) a rigid housing defining aninner volume (IV), a fluid inlet port and a fluid outlet port, whereinthe inner volume is in fluid flow communication with the fluid inletport and the fluid outlet port; and (ii) a solid support disposed withinthe housing and defining a fluid contacting surface with a surface area(SA) capable of sequestering an activated leukocyte and/or an activatedplatelet if present in a body fluid entering the housing via the fluidinlet port, wherein the SA/IV ratio is greater than 80 cm⁻¹; and (b)introducing a body fluid from a subject into the housing via the fluidinlet port under conditions that permit sequestration of an activatedleukocyte and/or an activated platelet on the fluid contacting surfaceof the solid support.
 34. The method of claim 33, further comprising (c)treating the leukocyte and/or platelet sequestered in step (b) toinhibit release of a pro-inflammatory substance or to deactivate theleukocyte and/or the platelet.
 35. The method of claim 34, wherein theleukocyte or the platelet is sequestered for a time sufficient toinhibit the release of the pro-inflammatory substance or to deactivatethe leukocyte or the platelet.
 36. The method of claim 35, wherein theleukocyte and/or the platelet is sequestered for at least one minute.37-61. (canceled)
 62. A cartridge for treating activated leukocytes,activated platelets, or both activated leukocytes and activatedplatelets, comprising: (a) a rigid housing defining an inner volume(IV), a fluid inlet port and a fluid outlet port, wherein the innervolume is in fluid flow communication with the fluid inlet port and thefluid outlet port; and (b) a solid support disposed within the housingand defining a fluid contacting surface with a surface area (SA) capableof sequestering an activated leukocyte and/or an activated platelet ifpresent in a body fluid entering the housing via the fluid inlet port,wherein the SA is greater than 2.6 m².
 63. The cartridge of claim 62,wherein the SA is in the range from 3.0 m2 to 10.0 m2.
 64. The cartridgeof claim 63, wherein the SA is in the range from 3.0 m2 to 5.0 m2. 65.The cartridge of claim 62, wherein the solid support is a membrane.66-70. (canceled)
 71. The cartridge of claim 62, wherein the IV is lessthan 300 cm³.
 72. The cartridge of claim 71, wherein the IV is less than150 cm3.
 73. The cartridge of claim 72, wherein the IV is less than 100cm³. 74-111. (canceled)